The number of suicide deaths in Japan has continued to be high, and is a pressing social problem. Although the weekly distribution of suicide deaths has been documented, no nationwide analysis has yet been conducted. In the present study, the ratios of the number of suicide deaths per day, by day of the week, and on weekdays relative to holidays were calculated using the data for all suicide deaths recorded in 2003. The suicide deaths recorded on holidays were treated as the reference, and a confidence interval of 95% (95% CI) was used. We calculated the suicide death ratios among men and women of all ages (men:23,396, women:8,713, total:32,109) and also among those of productive age (age:15-64 years, men:18,552, women:5,481, total:24,033). Among men of all ages, the suicide death ratio on Mondays was found to be significantly high at 1.49 (95% CI:1.04-2.14), and the ratios were found to decrease over the course of the week from Monday to Friday. On each weekday, the suicide death ratios among men of productive age were found to be higher than those among men of all ages. Among women, the suicide death ratios on any weekday were found to be higher than 1, but there was no significant difference between the days. Among both men and women, the number of suicide deaths on holidays was lower than that on weekdays. This study revealed that the number of suicide deaths recorded per day on Mondays is 1.5 times higher than that on holidays among men. This suggests that the structure of the work week may possibly influence suicide deaths among men. Future discussions regarding the arrangement and distribution of weekly holidays should be conducted in order to reduce the number of suicide deaths.