Seed plants, such as rice, wheat, soybean, and corn, are very important as food sources for people around the world. Thus, as the world's population increases, it is necessary that food quality and production are developed. Selective breeding of plants requires seed preservation at low temperature. Changes in the freezing and non-freezing water of unpolished rice grains at each growth stage after flowering were measured by differential scanning calorimetry (DSC). The weight of water in unpolished rice grains rapidly increased until 10 days after flowering. Twenty days after flowering, the weight of water decreased. The length of unpolished rice grains remained unchanged after 10 days. The content of non-freezing water peaked at the 10th day. The content in non-freezing water was constant after 20 days. The glass transition temperature was constant at about -100℃ up to 40 days after flowering. The glass transition temperature was abruptly increased after the 40th days, when the freezing (unbound) water in the rice grains was no longer observed in the unpolished rice. The glass transition temperature of the unpolished rice is dependent on the moisture content of the grains.