An integrator of a vehicular radar system has multiple switches and multiple capacitors, which are connected with the switches, for each one of photoreceptive elements. The integrator integrates light reception signals, which are output from the photoreceptive elements, by switching the switches to a connected state one after another in a predetermined order at a predetermined time interval until a predetermined time passes after every emission of the laser light and by switching the switches to the connected state one after another in a predetermined order at a predetermined time interval if the laser light is emitted predetermined times. Thus, the integrator can integrate the light reception signals, which are output from the multiple photoreceptive elements, in parallel.