Multiple photodetectors that photoelectric convert incident light to output a pixel signal; multiple analog/digital (A/D) convertors that A/D convert a plurality of pixel signals that are output by the photodetectors in parallel in a plurality of systems; a retaining unit that retains the pixel signals A/D converted in parallel by the A/D convertors in an aligned manner in one direction, to be arranged in reading order from a first pixel signal to a final pixel signal; and multiple transfer units that transfer the pixel signals arranged and retained by the retaining unit, sequentially from the first pixel signal from a first-pixel-signal retaining position toward a final-pixel signal retaining position of the retaining unit are included.