Litterfall and seed production is a vital process of nutrient cycling, primary productivity, and regeneration in a forest ecosystem, yet limited attention has been paid in a secondary forest in Japan. This study aims to characterize the litterfall and seed production in a warm temperate secondary forest, by comparing with that in other old-growth forests, and by determining the temporal changes, using the 6-year litterfall and seed production dataset in the Kaisho forest, Aichi prefecture. Our results indicate that the amount of annual total litterfall in a warm temperate secondary forest is intermediate between deciduous broadleaved and evergreen broadleaved forests. A significant positive correlation between mean annual total litterfall and the basal area (BA) was detected when the data in evergreen coniferous forests were removed. In the Kaisho secondary forests, total litterfall and its temporal variation differed among the three plots, total litterfall was related to the BA of evergreen tree species. Temporal fluctuation in total litterfall might be due to the decrease in BA caused by Japanese oak-wilt disease during 2008- 2013.