©2015. American Geophysical Union. We examined the effects of Asian monsoon rainfall on CH<inf>4</inf> absorption of water-unsaturated forest soil. We conducted a 1year continuous measurement of soil CH<inf>4</inf> and CO<inf>2</inf> fluxes with automated chamber systems in three plots with different soil characteristics and water content to investigate how temporal variations in CH<inf>4</inf> fluxes vary with the soil environment. CH<inf>4</inf> absorption was reduced by the "Baiu" summer rainfall event and peaked during the subsequent hot, dry period. Although CH<inf>4</inf> absorption and CO<inf>2</inf> emission typically increased as soil temperature increased, the temperature dependence of CH<inf>4</inf> varied more than that of CO<inf>2</inf>, possibly due to the changing balance of activities between methanotrophs and methanogens occurring over a wide temperature range, which was strongly affected by soil water content. In short time intervals (30min), the responses of CH<inf>4</inf> and CO<inf>2</inf> fluxes to rainfall were different for each plot. In a dry soil plot with a thick humus layer, both fluxes decreased abruptly at the peak of rainfall intensity. After rainfall, CO<inf>2</inf> emission increased quickly, while CH<inf>4</inf> absorption increased gradually. Release of accumulated CO<inf>2</inf> underground and restriction and recovery of CH<inf>4</inf> and CO<inf>2</inf> exchange between soil and air determined flux responses to rainfall. In a wet soil plot and a dry soil plot with a thinner humus layer, abrupt decreases in CH<inf>4</inf> fluxes were not observed. Consequently, the Asian monsoon rainfall strongly influenced temporal variations in CH<inf>4</inf> fluxes, and the differences in flux responses to environmental factors among plots caused large variability in annual budgets of CH<inf>4</inf> fluxes.