The effects of the environmental temperature during the early development of seeds on the characteristics of the endosperm starch were investigated using near-isogenic lines and induced mutants of rice. The components of starch and pasting characteristics of starch granules varied by the environmental temperature. The lower temperature increased the amylose content and the ratios of short chain to long chain of amylopectin in endosperm starch. Moreover, the starch granules of rice plants grown under the lower temperature were more gelatinized than those grown under the higher temperature.