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 physical movement data of a subject； and a determination unit that calculates an overall average and a standard deviation of the physical movement data, sets a value, as a threshold, which is obtained by adding a value obtained by multiplying the standard deviation by a predetermined coefficient to the overall average, and determines that a region exceeding the threshold is an awakening stage.SELECTED DRAWING: Figure 7【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、被験者の体動データを取得するデータ取得部と、前記体動データの全体平均と標準偏差を算出し、前記標準偏差に所定の係数を乗算した値を前記全体平均に足し合わせた値を閾値として設定し、前記閾値を超える領域を覚醒段階と判定する判定部と、を有する。【選択図】図７
