To estimate a sleep stage from acquired physical data readily with higher accuracy.SOLUTION: A sleep stage determination device includes: a data acquisition unit for acquiring respiration data of a subject； and a determination unit that calculates an average and a standard deviation of the number of times of respiratory per unit time on the basis of the respiration data, sets a value, as a threshold, which is obtained by multiplying a variation coefficient obtained by dividing the standard deviation by the average, by a predetermined coefficient, and determines that a region equal to or lower than the threshold is a non-REM sleep stage.SELECTED DRAWING: Figure 5【課題】取得した身体データから、簡便かつより高い精度で睡眠段階を推定する【解決手段】睡眠段階判定装置は、被験者の呼吸データを取得するデータ取得部と、前記呼吸データに基づいて、単位時間当たりの呼吸数の平均値と標準偏差を算出し、前記標準偏差を前記平均値で除算した変動係数に所定の係数を乗算した値を閾値として設定し、前記閾値以下の領域をノンレム睡眠段階と判定する判定部と、を有する。【選択図】図５
