We developed ring-width chronologies for living trees of Japanese beech at two forest sites on the northern-most part of Honshu Island, Japan. A statistical threshold (running expressed population signal) yielded these site chronologies spanning 1853-1994 (142 years) and 1867-1994 (128 years). We examined two factors, climate and masting, that could affect the variations of radial growth. The response function analysis revealed that the ring width correlated positively with July and August temperatures of the previous growth year. The optimal radial growth of Japanese beech may largely depend on a warm previous summer with above-average temperatures. The years of good masting coincided mostly with those showing abrupt growth depression, although only the short-term records of masting were available.