The seasonal and daily activity patterns of 15 Japanese badgers (Meles meles anakuma) were studied using radio-telemetry and a video monitoring system from April 1997 to March 2001 in Yamaguchi City, Western Honshu, Japan. The badgers were primarily nocturnal, and there were no differences between the daily activity patterns of males and females. The badgers were sometimes active in the daytime; breeding females, in particular, would often forage during the day, in spring. Between July and October, they usually emerged from their setts around sunset and returned around sunrise. The time between emergence and return became shorter after November. From January to February, most activity ceased, and the badgers stayed in their setts most of the time. Time spent outside the sett was longest in summer and autumn. Activity of Japanese badgers seems to be influenced by the day-night cycle, reproduction, temperature, and food availability.