To accurately estimate sleepiness by using motions of a mouth.SOLUTION: A sleepiness estimation device comprises imaging means (100) for taking a face image of a driver of a vehicle, detecting means (210) for detecting duration of motions of a mouth of the driver and presence or absence of their periodicity on the basis of the face image, determining means (220) for determining a type of the motions of the mouth on the basis of the duration and the presence or absence of the periodicity, and estimating means (230) for estimating sleepiness of the driver on the basis of the type of the motions of the mouth.SELECTED DRAWING: Figure 1【課題】口の動きを利用して眠気を精度良く推定する。【解決手段】眠気推定装置は、車両の運転者の顔画像を撮像する撮像手段（１００）と、顔画像に基づいて、運転者の口の動きの継続時間及び周期性の有無を検出する検出手段（２１０）と、継続時間及び周期性の有無に基づいて、口の動きの種類を判定する判定手段（２２０）と、口の動きの種類に基づいて、運転者の眠気を推定する推定手段（２３０）とを備える。【選択図】図１
