The wearable measurement device includes a mounting part for mounting the device to a human body, a variation detection part detecting the movement of a predetermined portion of the human body while not being in contact with the predetermined portion, and a measurement part measuring the number of predetermined motions or time of motion based on the movement detected by the variation detection part. The variation detection part includes a light emitting unit and a light receiving unit, makes the light emitting unit emit light and the light receiving unit detect reflection light reflected at a predetermined portion, detects a distance from the predetermined portion and outputs an electric signal (voltage or current) in accordance with the detected distance at a predetermined sampling cycle.
