A photodetector of an OCT device is provided with: a silicon substrate comprised of a semiconductor of a first conductivity type, having a first principal surface and a second principal surface opposed to each other, and having a semiconductor region of a second conductivity type formed on the first principal surface side； and charge transfer electrodes provided on the first principal surface and transferring generated charges. In the silicon substrate, an accumulation layer of the first conductivity type having a higher impurity concentration than the silicon substrate is formed on the second principal surface side, and an irregular asperity is formed in a region opposed to at least the semiconductor region, in the second principal surface. The region in which the irregular asperity is formed on the second principal surface of the silicon substrate is optically exposed.
