It is well known that breeding activity of amphibian species is affected by weather factors such as temperature and rainfall. Although some studies suggested that their activity was affected by lunar cycle, few studies have examined this effect till now. We conducted surveys on the breeding activities of the Japanese toad, Bufo japonicus formosus, at two sites, Minami-ohsawa, Hachioji-shi, Tokyo in 2011, and Yamakita-machi, Kanagawa Prefecture in 1992-1994. We analyzed these census data using meteorological data from the nearby AMeDAS stations to evaluate the effects of weather factors and lunar cycle on the breeding activities of toads. Statistical analyses were performed using GLMs with negative binomial　errors. The best models were selected from all models obtained from all subset approach, based on AIC_C. The result showed that weather factors including dry period and daily maximum wind speed affected significantly breeding activities of toads at Yamakita, but the most important factor was lunar phase at both study sites: when the moon got waned, the breeding activity became higher. The ecological significance of the effect of lunar cycle is not known at present. Breeding in dark nights may avoid predation, or gravitational changes due to lunar cycle may help the synchronization of the reproductive timing. Further research will be needed to understand the effect of lunar cycle.