A distance measurement device comprising a light-sending unit for sending pulsed light toward an object of measurement where a distance thereto is measured, a light-receiving unit for receiving incident light including pulsed reflection light reflected by the object, a distance measurement unit for measuring the time from the sending of the pulsed light to the receiving of the incident light and calculating the distance to the object, and an interference detection unit for determining whether interference light exists in the incident light, based on the intensity of the incident light.