In accordance with an irradiation position of pulsed light, a selecting unit outputs a first transfer signal to a first transfer electrodes and outputs a second transfer signal to a second transfer electrodes, to allow signal charges to flow into first and second signal charge-collecting regions of a pixel corresponding to the irradiation position, and outputs a third transfer signal to a third transfer electrodes to allow unnecessary charges to flow into an unnecessary charge-discharging regions of a pixel other than the pixel corresponding to the irradiation position. An arithmetic unit reads out signals corresponding to respective quantities of signal charges collected in the first and second signal charge-collecting regions of the pixel selected by the selecting unit, and calculates a distance to an object based on a ratio between a quantity of signal charges collected in the first signal charge-collecting regions and a quantity of signal charges collected in the second signal charge-collecting regions.