Mental Health Legal Developments in Japan

In Japan, workplace mental-health law has developed from a relatively narrow concept of occupational safety and compensation for overwork into a broader compliance framework covering psychological safety, harassment, stress checks, privacy, return-to-work, reasonable work adjustments, and employer preventive duties.

The most important recent development is the expansion of the stress-check obligation to workplaces with fewer than 50 workers, following the 2025 amendment to the Industrial Safety and Health Act. The Ministry of Health, Labour and Welfare (MHLW) has also issued implementation guidance for small workplaces, with the new obligation scheduled for 1 April 2028.

1. Meaning and scope of mental-health legal protection

Mental-health protection in Japanese employment law is not based on one single statute. It arises from several overlapping legal regimes:

1. Labour Contract Act, Article 5 — employer's duty to give consideration to employees' safety, including mental and physical health.
2. Industrial Safety and Health Act — workplace health management, medical examinations, stress checks and measures following high-stress findings.
3. Industrial Accident Compensation Insurance Act — compensation where mental disorders or suicide are occupationally caused.
4. Act on Comprehensive Promotion of Labour Policies — workplace power-harassment prevention framework.
5. Equal Employment Opportunity Act — protection against pregnancy/maternity-related harassment and related psychological harm.
6. Act on the Protection of Personal Information — particularly important for medical and mental-health information.
7. Civil Code — damages for breach of contractual or tortious obligations.

MHLW expressly recognizes that employers owe a safety consideration obligation (anzen hairyo gimu) under Article 5 of the Labour Contract Act, including mental-health protection.

2. Major recent development: stress checks for small workplaces

Historically, Japan's statutory stress-check system principally applied to workplaces with 50 or more workers.

The 2025 amendment to the Industrial Safety and Health Act significantly changes this position. The amendment was promulgated on 14 May 2025, and makes stress checks mandatory even for workplaces with fewer than 50 workers.

The obligation for small workplaces is scheduled to commence on 1 April 2028.

Legal significance

This is important because smaller enterprises traditionally had fewer formal mental-health structures.

The new regime moves Japan toward:

universal preventive mental-health screening rather than protection only after a mental-health problem becomes visible.

MHLW published a dedicated Small Workplace Stress Check Implementation Manual in February 2026, specifically addressing privacy protection and practical implementation for small businesses.

3. Protection of confidentiality and mental-health information

Mental-health information is particularly sensitive.

Employers should distinguish between:

• ordinary personnel information;
• health information;
• psychiatric diagnosis;
• medication information;
• stress-check results;
• occupational physician opinions;
• return-to-work assessments;
• counselling records.

The Toshiba case is particularly important because the Supreme Court recognized the private nature of psychiatric treatment, diagnosis and medication information.

Consequently, employers should not treat disclosure of a psychiatric diagnosis as an ordinary HR reporting obligation.

A legally safer approach is generally to obtain only the information necessary for:

• determining fitness for work;
• making workplace adjustments;
• deciding leave or return-to-work arrangements;
• preventing health deterioration;
• fulfilling statutory occupational-health obligations.

4. Employer duty may arise even without an employee's disclosure

One of the most important developments in Japanese mental-health jurisprudence is the rejection of the idea that:

"The employee did not tell HR about depression, therefore the employer cannot be responsible."

That proposition is too broad.

Where the employer can reasonably recognize deterioration in the employee's condition, the employer may have to take preventive measures even without a formal psychiatric disclosure.

This principle was strongly established in Toshiba Corporation v. employee.

5. Case Law 1 — Dentsu Case

Supreme Court, 24 March 2000

Dentsu Case

This is the leading Japanese authority concerning work-related depression and suicide.

A young employee worked extremely long hours, developed depression and eventually committed suicide. The Supreme Court held the employer responsible for failing to take appropriate measures despite awareness of excessive working hours and deteriorating health.

Importance

The case established that employers must consider:

• excessive working hours;
• deterioration in health;
• warning signs;
• workload;
• managerial supervision;
• whether work should be reduced.

The Court also rejected an overly simplistic approach to the employee's personality. A personality falling within the normal range of individual differences cannot automatically be used to substantially reduce employer liability.

Practical rule

Long hours + observable deterioration + failure to intervene = significant safety-duty risk.

6. Case Law 2 — Toshiba Mental-Health Case

Supreme Court, Second Petty Bench, 24 March 2014

This is one of the most important modern Japanese mental-health decisions.

The employee suffered mental-health deterioration while performing demanding work and eventually became unable to work.

The Supreme Court held that mental-health information is highly private and that an employee may reasonably hesitate to disclose psychiatric treatment or diagnosis because of concerns about workplace evaluation.

Most importantly, the Court held that an employer can have a safety obligation even when the employee has not positively disclosed the mental-health condition, where the employer could recognize deterioration.

The Court also rejected reducing damages merely because the employee had failed to disclose the psychiatric condition.

Legal principle

The employer must look not only at:

"What did the employee tell us?"

but also:

"What could a reasonable employer observe?"

HR consequence

Managers should document observable warning signs such as:

• repeated absences;
• severe fatigue;
• sudden deterioration in performance;
• insomnia complaints;
• emotional instability;
• requests for workload reduction;
• unusual behaviour;
• excessive overtime.

7. Case Law 3 — National Police / Police Officer Mental-Health Case

The Supreme Court has also applied the employer's mental-health safety obligation in the public-sector context.

The Court recognized that the employer's duty to protect physical and mental health from excessive fatigue and psychological burden applies even in the relationship between a prefecture and a police officer.

Importance

This demonstrates that the underlying principle is not limited to ordinary private corporations.

The assessment requires consideration of the totality of working circumstances, including:

• workload;
• psychological pressure;
• managerial conduct;
• work environment;
• working hours;
• organizational circumstances.

HR lesson

An employer cannot assume that a stressful occupation automatically eliminates its safety obligations.

8. Case Law 4 — Yamada Seisakusho Case

Mental-health suicide / occupational-causation litigation

The Yamada Seisakusho litigation is important because it illustrates the difficult questions surrounding:

• causation;
• predictability;
• workload;
• workplace circumstances;
• employee mental-health deterioration.

MHLW identifies it among its mental-health case materials specifically as a case involving the relationship between workload, causation and foreseeability.

Legal importance

Mental-health liability is not automatically established merely because an employee developed depression.

Courts generally examine:

1. what work the employee actually performed;
2. the intensity and duration of the work;
3. interpersonal circumstances;
4. harassment or managerial behaviour;
5. symptoms and behavioural changes;
6. medical evidence;
7. whether the employer could reasonably foresee the risk.

Thus, causation must be established through the surrounding facts rather than merely the existence of a diagnosis.

9. Case Law 5 — Higashi-Kakogawa Nursery School Case

This case concerns suicide following a period of work-related psychological deterioration.

MHLW describes it as a case in which the employer's safety consideration obligation was recognized, although the damages were reduced.

Importance

It illustrates an important distinction:

Employer liability and the amount of damages are separate questions.

A court may find:

• occupational contribution;
• employer breach;
• causal connection;

while still reducing damages depending upon the circumstances of the particular case.

Practical lesson

Employers should not assume that proving some employee contribution automatically defeats liability.

The more important issue is whether the employer fulfilled its own preventive obligations.

10. Case Law 6 — Toyota-related mental-health / power-harassment litigation

Japanese courts have also increasingly dealt with cases involving the combination of:

• excessive workload;
• managerial pressure;
• power harassment;
• depression;
• suicide;
• workers' compensation.

One Toyota-related case concerned an employee whose family argued that excessive work and continuing power harassment caused depression and suicide. The litigation examined whether the occupational circumstances were sufficient to establish work causation.

Importance

This reflects the convergence between:

mental-health law + working-time law + power-harassment law + workers' compensation law.

A company therefore cannot treat psychological harm as purely a medical matter.

The underlying workplace conditions may themselves become legally relevant.

11. Case Law 7 — Mental-health privacy and employer investigation

Japanese case law also recognizes an important boundary on employer investigation.

A court has rejected the proposition that an employer must investigate whether an employee has a psychiatric disorder merely because no obvious abnormal behaviour exists. Such an investigation could itself create serious privacy concerns.

Why this matters

The law therefore requires a balanced approach:

Employer must:

• monitor workplace conditions;
• respond to observable warning signs;
• prevent excessive workloads;
• provide occupational-health mechanisms.

Employer should not:

• indiscriminately investigate employees' psychiatric histories;
• demand unnecessary diagnoses;
• circulate medical information;
• assume that every performance problem is a mental-health problem.

The legal direction is therefore:

active prevention without unnecessary medical surveillance.

12. Stress-check system: legal development

Japan's stress-check regime has existed since 2015.

The basic system involves:

1. psychological-stress assessment;
2. individual notification of results;
3. high-stress worker identification;
4. physician interview opportunities;
5. employer measures based on occupational-health findings.

The system is not designed merely to create an HR database.

Its principal purpose is preventive occupational health.

MHLW maintains separate statutory guidance for both the stress-check system and broader mental-health measures.

13. 2026 development: collective analysis and privacy

A particularly important 2026 development concerns group/collective analysis of stress-check information.

An amendment to the Industrial Safety and Health Regulations was promulgated on 30 June 2026, with implementation scheduled for 1 April 2027.

The amendment addresses how collective analysis should be conducted while ensuring that individual employees cannot be identified.

Practical significance

Employers increasingly want to use workforce analytics to identify:

• burnout hotspots;
• high-pressure departments;
• managerial problems;
• excessive workloads;
• organizational stress.

But aggregated analytics must not become a mechanism for indirectly identifying individual medical information.

14. Mental health and power harassment

Japan's power-harassment framework has significantly strengthened mental-health protection.

Power harassment can include conduct involving:

• abuse of authority;
• excessive or unreasonable demands;
• isolation;
• humiliating treatment;
• persistent verbal abuse;
• inappropriate managerial pressure.

Where such conduct causes psychiatric injury, the employer may face several forms of exposure:

• civil damages;
• workers' compensation implications;
• breach of safety consideration obligation;
• harassment-prevention compliance problems;
• management accountability.

Therefore, harassment investigations should consider not only the conduct itself but also mental-health consequences.

15. Mental health and working hours

Mental-health legal developments cannot be separated from working-time compliance.

Excessive overtime may become evidence of:

• breach of safety consideration obligation;
• occupational causation;
• foreseeable mental-health risk;
• inadequate workload management;
• failure of managerial supervision.

The Dentsu case remains particularly important because it demonstrates the connection between excessive working hours, depression and employer responsibility.

Employers should therefore monitor more than statutory overtime thresholds.

A worker can face serious psychological deterioration even before a simple numerical threshold captures the entire risk.

16. Mental-health leave and return-to-work

Japanese law does not create one universal statutory entitlement called "mental-health leave" applicable to every employee in every circumstance.

Instead, employers commonly rely upon:

• company sick-leave rules;
• work rules;
• annual paid leave;
• occupational-health measures;
• medical certificates;
• return-to-work procedures;
• reasonable workplace adjustments.

This makes the drafting of work rules and leave policies extremely important.

A policy should clearly establish:

• notification procedures;
• medical-document requirements;
• maximum leave periods;
• communication during leave;
• occupational physician involvement;
• return-to-work assessment;
• trial attendance where appropriate;
• relapse management;
• confidentiality;
• termination consequences after exhaustion of leave.

17. Return-to-work decisions require care

An employee returning after depression or another mental-health condition should not automatically be treated as either:

"fully fit" or "unfit."

A graduated approach may be more appropriate:

The employer must balance:

• employee privacy;
• safety;
• operational requirements;
• medical evidence;
• non-discrimination;
• contractual obligations.

18. Mental-health discrimination risk

Mental illness can also intersect with broader employment discrimination principles.

Risk areas include:

• refusing recruitment because of a psychiatric history;
• automatic exclusion from promotion;
• dismissal solely because an employee has received psychiatric treatment;
• unreasonable demands for medical information;
• treating mental illness as misconduct;
• denying reasonable workplace adjustments;
• retaliating against employees who report psychological harm.

The correct legal approach is to assess the employee's actual ability to perform work and the reasonable workplace measures available, rather than relying on stereotypes.

19. Occupational accident compensation

A mental disorder can qualify as an occupational injury where the legal requirements concerning work-related psychological burden and causation are satisfied.

Important evidence may include:

• working hours;
• workload;
• job changes;
• interpersonal conflicts;
• harassment;
• performance pressure;
• disciplinary action;
• medical records;
• contemporaneous complaints;
• emails and messages;
• witness evidence;
• stress-check information.

Thus, HR recordkeeping has become increasingly important.

20. AI and mental-health monitoring

A newer compliance issue is the use of technology to identify workforce stress.

Examples include:

• absenteeism analytics;
• productivity monitoring;
• behavioural analytics;
• employee-survey analysis;
• AI-based attrition prediction;
• sentiment analysis;
• automated risk scoring.

These systems create significant legal risks if they attempt to infer:

"This employee is depressed."

from indirect behavioural information.

Mental-health information is highly sensitive, and the Toshiba principle demonstrates the importance of privacy and the reluctance of employees to disclose psychiatric information.

Accordingly, companies should avoid unnecessary individual-level mental-health profiling and establish strict controls over:

• purpose limitation;
• access;
• retention;
• human review;
• confidentiality;
• accuracy;
• employee notification;
• automated-decision governance.

21. What the 2025–2028 reforms mean for employers

The direction of Japanese law is increasingly preventive.

The 2025 Industrial Safety and Health Act amendment expressly strengthens workplace mental-health measures and expands the stress-check obligation.

MHLW has already prepared implementation material specifically for small workplaces, emphasizing practical implementation and privacy protection.

Therefore, employers should prepare before the 2028 deadline rather than waiting until the statutory obligation becomes operational.

22. Recommended employer compliance framework

A robust Japanese mental-health compliance program should include:

A. Governance

• Board-level responsibility.
• HR and occupational-health ownership.
• Defined escalation procedures.
• Mental-health risk register.

B. Stress checks

• Proper administration.
• Confidentiality controls.
• High-stress employee procedures.
• Physician interview mechanism.
• Appropriate organizational analysis.

C. Working-time controls

• Accurate working-hour records.
• Overtime monitoring.
• Excessive-work alerts.
• Manager accountability.

D. Harassment prevention

• Power-harassment policy.
• Confidential reporting.
• Prompt investigation.
• Anti-retaliation safeguards.
• Corrective action.

E. Leave and return to work

• Clear mental-health leave rules.
• Medical assessment procedures.
• Gradual return mechanisms.
• Workload adjustments.
• Relapse-management protocols.

F. Privacy

• Restricted medical-data access.
• Need-to-know principle.
• Separate occupational-health records.
• Secure storage.
• Retention rules.

G. Documentation

Keep evidence of:

• stress-check implementation;
• manager training;
• employee complaints;
• workload interventions;
• occupational physician recommendations;
• return-to-work decisions;
• accommodations;
• harassment investigations.

23. Six core legal principles emerging from the case law

The Japanese case law can be summarized into six major principles:

1. Mental health is part of occupational safety

The employer's safety consideration obligation includes psychological as well as physical health.

2. Employee silence does not automatically protect the employer

Where deterioration is reasonably observable, the employer may have to intervene even without formal disclosure. Toshiba is the leading authority.

3. Excessive work is legally significant

Long working hours and excessive psychological burden can establish important evidence of employer responsibility. Dentsu remains the foundational case.

4. Medical privacy remains important

Employers cannot simply investigate or collect psychiatric information without considering privacy implications.

5. Harassment and mental health increasingly overlap

Power harassment can contribute to occupational mental disorders and resulting compensation disputes.

6. Prevention is replacing purely reactive protection

The expansion of stress checks to small workplaces demonstrates Japan's move toward systematic prevention and organizational risk management.

Conclusion

The direction of Japanese mental-health employment law is clearly toward proactive employer responsibility.

The historical model was largely:

overwork → illness → compensation dispute.

The modern model is increasingly:

risk identification → stress assessment → preventive intervention → confidentiality → accommodation → return-to-work → continuous monitoring.

The most significant recent legislative development is the extension of mandatory stress checks to workplaces with fewer than 50 workers from 1 April 2028, together with the 2026 regulatory work on privacy-conscious collective analysis.

For employers, the central lesson from Dentsu, Toshiba and the other mental-health cases is that compliance cannot depend solely on whether an employee formally says, "I have a mental-health condition." Employers must also pay attention to workload, observable deterioration, harassment, working hours, organizational stressors and appropriate preventive measures.

This is a general legal research overview, not case-specific legal advice.