PURPOSE: The impact of daily total physical activity level on premature deaths has not been fully clarified in non-Western, relatively lean populations. We prospectively examined the association between daily total physical activity level (METs/day) and subsequent risk of all-cause mortality and mortalities from cancer, heart disease, and cerebrovascular disease. METHODS: A total of 83,034 general Japanese citizens ages 45-74 years who responded to the questionnaire in 1995-1999 were followed for any cause of death through December 2005. Mutlivariate-adjusted hazard ratios were calculated with a Cox proportional hazards model controlling for potential confounding factors. RESULTS: During follow-up, a total of 4564 deaths were recorded. Compared with subjects in the lowest quartile, increased daily total physical activity was associated with a significantly decreased risk of all-cause mortality in both sexes (hazard ratios for the second, third, and highest quartiles were: men, 0.79, 0.82, 0.73 and women, 0.75, 0.64, 0.61, respectively). The decreased risk was observed regardless of age, frequency of leisure-time sports or physical exercise, or obesity status, albeit with a degree of risk attenuation among those with a high body mass index. A significantly decreased risk was similarly observed for death from cancer and heart disease in both sexes, and from cerebrovascular disease in women. CONCLUSION: Greater daily total physical activity level, either from occupation, daily life, or leisure time, may be of benefit in preventing premature death.