Liability for Negligence in Care Obligations — Japan

In Japanese employment law, “care obligations” generally refer to the employer’s duty to give necessary consideration to the employee’s safety, health and well-being while performing work. The central statutory provision is Article 5 of the Labour Contract Act, which requires an employer to take necessary measures so that a worker can work while maintaining the safety of their life and body. “Safety” is interpreted to include physical and mental health.

1. Meaning of the Employer’s Care Obligation

The obligation is not limited to preventing physical accidents. Depending on the circumstances, it can cover:

• workplace safety and dangerous equipment;
• excessive working hours and accumulated fatigue;
• psychological stress and mental-health risks;
• occupational diseases;
• adequate training and supervision;
• appropriate working conditions;
• prevention of foreseeable workplace hazards;
• responding appropriately when an employee shows signs of serious health deterioration.

The Ministry of Health, Labour and Welfare explains that the required measures depend on the worker’s occupation, work content, workplace and specific circumstances rather than being identical for every employee.

2. When Does Negligence Arise?

An employer may face liability where:

1. a duty of care existed;
2. the employer or supervisor failed to take reasonably necessary precautions;
3. the risk was foreseeable, or the circumstances required appropriate preventive action;
4. the failure caused injury, illness or other legally compensable damage; and
5. the necessary causal connection between the breach and the damage can be established.

The breach may arise through action or omission. For example, continuing to assign excessive work after becoming aware of an employee's deteriorating health can potentially constitute a breach.

Important Case Laws

1. Self-Defense Forces Case — Supreme Court, 25 February 1975

This is one of the foundational Japanese cases concerning the safety consideration obligation (安全配慮義務).

The Supreme Court recognised that an employer-like authority has an obligation arising from the employment-related relationship to protect workers from dangers associated with the working environment and performance of their duties.

The case established the fundamental concept that the duty of care can exist even where the employment contract does not expressly spell out every individual safety obligation.

This principle later became reflected expressly in Article 5 of the Labour Contract Act. The Ministry of Health, Labour and Welfare specifically identifies this case as an important precedent concerning Article 5.

Legal significance:
It provides the foundation for treating safety and health protection as an incidental obligation accompanying the employment relationship.

2. Kawagi Case — Supreme Court, 10 April 1984

The Supreme Court further developed the employer's safety obligation.

The content of the obligation depends on the circumstances, including:

• the worker's occupation;
• the nature of the work;
• the workplace;
• the foreseeable risk of accident or disease;
• available methods for preventing the risk; and
• the level of knowledge and technology relevant to the risk.

The MHLW expressly identifies Kawagi as a leading case concerning the safety consideration obligation under Article 5.

Legal significance:
There is no single universal checklist for every workplace. The employer's obligation is determined according to the specific risk and circumstances of the employment.

3. Dentsu Case — Supreme Court, 24 March 2000

This is one of the most important Japanese cases concerning overwork, mental health and employer liability.

An employee of a major advertising company worked extensive overtime for a prolonged period, developed depression and subsequently committed suicide.

The Supreme Court held that the employer had a duty to ensure that the employee's physical and mental health was not damaged by excessive accumulation of fatigue and psychological stress resulting from work. Supervisors exercising managerial authority were also required to exercise that authority consistently with this obligation.

Legal significance:
The case demonstrates that the care obligation extends beyond physical workplace accidents to mental-health consequences of excessive work.

4. Mitsubishi Motors Hub Case — Supreme Court, 8 February 2012

Although this was a criminal negligence case rather than a conventional employment dispute, it is useful for understanding the broader Japanese principle of negligence and foreseeable risk.

The Supreme Court considered whether responsible personnel had failed to take necessary corrective measures after becoming aware of serious risks associated with a vehicle component. The Court recognised a duty to take necessary measures, including recall-related measures, where the risk and the possibility of preventing the resulting harm were sufficiently established.

Legal significance:
It illustrates the importance of:

• knowledge of a risk;
• foreseeability;
• ability to prevent the harm; and
• causal connection between omission and resulting damage.

These concepts are relevant when analysing negligence in workplace-care situations as well.

5. Asbestos / Occupational Health Case — Supreme Court

Japanese Supreme Court decisions concerning asbestos exposure and occupational health have emphasised that workplace safety legislation imposes concrete obligations to prevent health impairment.

The Industrial Safety and Health Act requires employers to take measures against various health hazards, including exposure to dangerous substances and harmful workplace conditions. The Supreme Court has considered whether regulatory and protective measures were sufficient in light of scientific and technical knowledge concerning occupational risks.

Legal significance:
An employer's care obligation can be affected by the state of scientific and technical knowledge concerning the relevant workplace risk.

Where a serious occupational hazard is reasonably known, simply ignoring the risk can expose an employer to liability.

6. 2025 Supreme Court Police Inspector Case — 7 March 2025

The Supreme Court recently reaffirmed the principle of an employer's duty to protect workers from excessive fatigue and psychological burden.

The case concerned a police inspector who committed suicide after a significant increase in workload. The circumstances included substantial overtime, consecutive periods of work, additional burdens and a known stress-test result. The Supreme Court stated that an employer has a duty of care to ensure that the worker's physical and mental health is not impaired by excessive accumulation of fatigue or psychological burden.

The Court also explained that the circumstances surrounding the work must be considered comprehensively, rather than applying a single numerical threshold mechanically.

Legal significance:
The decision demonstrates that modern Japanese care obligations continue to encompass mental health, workload management and supervisory responsibilities.

3. Liability for Negligence in Different Situations

A. Excessive Workload

If an employer knowingly allows excessive workloads to continue, particularly where there are indications of serious fatigue or psychological deterioration, liability may arise.

Relevant considerations include:

• overtime;
• consecutive working days;
• insufficient rest;
• workload increases;
• employee complaints;
• health warnings;
• supervisor knowledge; and
• whether workload could reasonably have been reduced.

The Dentsu and 2025 Supreme Court decisions are particularly important here.

B. Mental-Health Problems

The care obligation includes mental health. An employer should not treat workplace mental-health risks as completely outside its legal responsibility.

Where management knows, or should reasonably know, that work is creating a serious psychological burden, failure to take appropriate measures may contribute to liability.

C. Physical Workplace Hazards

Employers must comply with the Industrial Safety and Health Act and related regulations concerning:

• machinery;
• hazardous substances;
• ventilation;
• workplace conditions;
• protective equipment;
• safety education; and
• occupational-health measures.

The statutory framework expressly requires employers to take measures to prevent health impairment.

D. Failure to Supervise

The obligation does not necessarily stop at the company's senior management.

A person exercising authority to direct and supervise employees may also have responsibilities to exercise that authority consistently with the employer's safety and health obligations. This was specifically recognised in the Dentsu decision.

4. Article 5 of the Labour Contract Act

Article 5 provides the statutory foundation:

“Consideration to the Safety of a Worker”

An employer must provide the necessary consideration so that a worker can perform work while ensuring the safety of their life and body.

Importantly, MHLW guidance states that “life, body, etc.” includes mental and physical health. It also explains that the precise content of the obligation depends upon the worker's occupation, work duties and workplace circumstances.

5. Relationship with Civil Liability

A breach of the care obligation may result in a claim for damages depending on the legal basis and facts of the case.

Potentially relevant consequences include compensation for:

• medical expenses;
• lost earnings;
• physical injury;
• mental suffering;
• occupational disease;
• disability; and
• in appropriate cases, death-related damages.

The precise cause of action and limitation rules depend on the circumstances and the legal relationship between the parties.

6. Key Elements for Establishing Employer Liability

7. Employer Compliance Measures

To reduce liability, employers should maintain:

1. appropriate health and safety systems;
2. reasonable workload management;
3. overtime monitoring;
4. health examinations and follow-up;
5. mechanisms for reporting workplace risks;
6. appropriate mental-health support;
7. safety training;
8. adequate supervision;
9. investigation of accidents and complaints; and
10. prompt corrective action when a foreseeable danger is identified.

The statutory framework makes clear that Article 5 does not replace the detailed requirements of occupational safety legislation; employers must comply with the specific requirements imposed by those laws as well.

Conclusion

Liability for negligence in care obligations under Japanese employment law is based on the principle that an employer must take necessary and reasonable steps to protect employees from foreseeable workplace risks. The obligation covers both physical and mental health, and its precise scope depends on the nature of the work, workplace conditions, foreseeable risks, available preventive measures and the employer's knowledge.

The Self-Defense Forces Case and Kawagi Case established the foundations of the safety consideration obligation, while the Dentsu Case significantly developed its application to excessive workload and mental health. More recent Supreme Court authority, including the 2025 police-inspector decision, confirms that excessive fatigue and psychological burden remain central considerations in determining an employer's care obligations.