Environmental conditions that affect rice production, such as air temper- ature, relative humidity, solar radiation, effective cation exchangeable capacity (ECEC) of the soil, and total nitrogen in irrigation water, were assessed for 4 paddy fields in Hoshino village, Fukuoka prefecture in Japan. Also, environ- mental factors that affected rice quality (physicochemical properties of rice grains and cooked rice) were identified using data during the beginning of a ripening period (20 days after heading) by principal component analysis. It was found that air temperature, diurnal range of temperature, solar radiation had major positive effects on rice quality. Also, a large diurnal range of tem- perature, which was advantageous for rice production, was observed locally in the rice terrace region.