The present invention includes an imager 1 having an automatic exposure stopping function, which are implemented therein, and includes an exposure time measuring unit 24 to measure the exposure time from the start of exposure to the stopping of exposure in the imager 1, a measurement distance calculating unit 21 to calculate the measurement distance to an object M on the basis of a displacement of the light receiving position in the imager 1, and a data output/storage unit 25 to output and/or store, as data related with acquisition of a distance actual value, which is an actual distance to the object, in a condition in which the measured exposure time and the measurement distance calculated with this exposure time are associated with each other.