What Is Karoshi?
Karoshi refers to death caused by excessive overwork and work-related stress.
In Japan, it includes deaths or suicides resulting from cerebrovascular and cardiovascular diseases, as well as mental disorders such as depression, when these conditions are strongly linked to long working hours and occupational stress.
In practice, working 80 to 100 hours of overtime per month is commonly referred to as the “karoshi line” and is used as an important benchmark for workers’ compensation recognition.
Definition and Main Causes of Karoshi
Legal definition:
Under Japan’s Act on Promotion of Preventive Measures against Karoshi and Other Overwork-Related Health Disorders, karoshi includes:
- Death caused by brain or heart diseases related to work
- Suicide caused by work-related mental disorders
- The onset of these serious health conditions
Main causes:
- Chronic sleep deprivation
- Prolonged excessive workloads with insufficient rest
- Severe psychological stress due to responsibility, pressure, or unrealistic targets
Warning signs:
Persistent fatigue, chest pain, cold sweats, shortness of breath, headaches, and general physical weakness may appear before serious illness or death.
Background Factors Behind Karoshi
Chronic Long Working Hours and Labor Shortages
- Workloads that exceed available manpower
- Uneven distribution of tasks concentrated on specific individuals
- Normalization of overtime, leading to continuous lack of rest and sleep
Workplace Environment and Corporate Culture
- Strong pressure from deadlines and performance quotas
- Hierarchical workplaces where communication is difficult
- IT environments that make employees reachable at all times, even outside working hours
Psychological and Physical Strain
- Irregular schedules and night work
- Jobs involving constant tension and responsibility
Individual Health Risks
- Overwork combined with conditions such as high blood pressure or diabetes
These factors often overlap and accumulate, turning long-term stress into serious health damage.
Statistics, Cases, and International Comparisons
1. Latest Karoshi Statistics
According to the 2024 fiscal year report (published in 2025) on workers’ compensation for karoshi-related cases by Japan’s Ministry of Health, Labour and Welfare:
- Record-high number of cases:
A total of 1,304 cases involving brain/heart disease and mental disorders were officially recognized, an increase of 196 from the previous year. - Sharp rise in mental disorders:
Out of 1,304 cases, 1,057 were related to mental illness, such as depression. This marks the fifth consecutive year of increase. - Brain and heart diseases:
247 cases were recognized, often involving chronic overwork or extreme workloads shortly before onset. - Karoshi-related suicides:
Among mental disorder cases, 89 involved suicide or attempted suicide.
2. Typical Karoshi Cases and Causes
Common factors leading to karoshi or karoshi-related suicide include excessive working hours, severe harassment, and overwhelming responsibility.
- IT engineers:
Continuous long overtime hours, often exceeding three hours of overtime per day shortly before sudden death. - Karoshi-related suicide (e.g., the Dentsu case):
Severe harassment and overtime exceeding 100 hours per month led to mental illness and ultimately suicide. - “Nominal managers”:
Employees treated as managers without real authority, excluded from overtime pay, and left without proper working-hour control.
3. International Comparison
Although karoshi was once considered a uniquely Japanese phenomenon, it has become a global issue.
- Global trends (WHO/ILO):
Over 740,000 people worldwide die each year from diseases linked to long working hours and occupational stress. Similar concepts exist in South Korea (gwarosa) and China (guolaosi). - Japan’s long working hours:
Japan remains among the higher-ranking OECD countries in working hours. More than 10% of male workers in their 30s and 40s work over 60 hours per week. - Europe’s approach:
Many European countries, especially in Northern Europe, emphasize work-life balance and higher paid leave utilization. - Global reforms:
Some countries, such as the UAE, have introduced a four-and-a-half-day workweek to improve productivity and quality of life.
“Karoshi” as an English Word
The term “karoshi” has been adopted directly into English.
- Oxford English Dictionary (OED):
Usage examples date back to 1988, and the term was officially included in the early 2000s. - Other dictionaries:
Major English dictionaries such as Merriam-Webster and Dictionary.com also list the word.
Dictionary definition:
“(in Japan) death caused by overwork or job-related exhaustion.”
Because English previously lacked a precise term for sudden death caused by overwork, karoshi entered the language as a loanword reflecting Japan’s work culture. Today, it is used internationally when discussing excessive working hours.
Conclusion and Reflection
Karoshi is not simply an individual problem caused by “working too hard.”
It is the result of deeply rooted social structures, corporate systems, and cultural expectations.
In Japan, strong emphasis on group harmony often makes it difficult for individuals to speak up, even when serious problems exist. Introducing alternative structures—such as learning from overseas work styles or appointing managers with different cultural backgrounds—may be one possible path toward change.
Most importantly, karoshi is not someone else’s problem.
It is an issue that can affect anyone.
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