The sleep state detection device and method, and the monitored person monitoring support system of the present invention detect the sleep state of the subject by the sleep state detection unit. Here, the presence or absence of a noise source that generates noise for the sleep state detected by the sleep state detection unit is detected, and the sleep state detection unit is controlled according to the detection result.本発明の睡眠状態検出装置および該方法ならびに被監視者監視支援システムは、対象者の睡眠状態を睡眠状態検出部で検出する。ここで、睡眠状態検出部で検出される睡眠状態に対するノイズを発生するノイズ源の有無が検出され、この検出結果に応じて前記睡眠状態検出部が制御される。
