A control unit makes a provisional determination as to whether or not a measurement subject is moving using a detection signal from a sensor that detects movement in bedding on which the measurement subject is sleeping. In the case where at least one of a first period, in which periods determined to have body movement repeat cyclically, and a second period, in which a period determined to have body movement continues for at least a predetermined amount of time, has occurred, at least one of a period in the first period determined to have body movement and the second period are corrected to a period of no body movement.
