The engineer was working on a new version of the popular Toyota Camry
One of Toyota's senior car engineers died from working too many hours, a Japanese labour bureau has found.
The 45-year-old man was developing a hybrid version of Toyota's successful Camry line at the time of his death.
In the two months leading up to his death, the man averaged more than 80 hours of overtime per month, his wife's lawyers said.
Workers in Japan often put in very long hours and "sudden death from overwork" is referred to as karoshi.
The ruling will allow his family to collect benefits from his work insurance, his wife's lawyers said.
The worker, whose name was not given, regularly worked nights and weekends and was frequently sent abroad. He died of ischemic heart disease in January 2006.
In a statement, Toyota offered its condolences and said it would monitor the health of its employees.
Workplace stress is common all over the world, but it is a huge problem in Japan, where karoshi was first recognised as a phenomenon in 1987.
Last year, a court in central Japan ordered the government to pay compensation to Hiroko Uchino, the wife of a 30-year-old Toyota employee who collapsed at work and died in 2002.