A light reception array unit receives light irradiated from an irradiation unit and reflected from an object, and outputs in parallel a pulse signal respectively output from a plurality of light reception units. A timer unit measures an elapsed time since an input of an irradiation timing signal. A response acquisition unit acquires a number of responses, which is a number of the light reception units outputting the pulse signal, at each fixed cycle timing, and outputs an adjusted number of responses obtained by subtracting a bias value from the number of responses or dividing the number of responses by the bias value. An address of a memory is associated with a timer value measured by the timer unit. A histogram generation unit integrates and stores, in a memory address specified from a timer value, the adjusted number of responses as data at that address.