 This study investigates the association between long working hours and health by defining long working hours as greater than 40 hours per week or 8 hours per day, minimizing the influence of shift work and analyzing previous studies to clarify epidemiological evidence. The results show that long working hours have significant adverse effects on most health outcomes, including depressive state, anxiety, sleep condition, and coronary heart disease. However, further studies are needed to appropriately deal with the definition of long working hours and shift work. This article was authored by Akira Bani and Akiko Tamakoshi.