Photodiode array

This photodiode array is equipped with a plurality of photodiodes formed on a semiconductor substrate. Each of the photodiodes has: a first semiconductor region of a first conductive type provided on the semiconductor substrate; a second semiconductor region of a second conductive type constituting the first semiconductor region and a photodetection region, and provided on one surface of the semiconductor substrate in relation to the first semiconductor region so as to surround a prescribed region; and a through electrode electrically connected to the second semiconductor region, and positioned inside a through-hole for passing between the one surface and the other surface of the semiconductor substrate so as to pass through the first semiconductor region and the prescribed region. Furthermore, the through electrode includes a section which widens from the one surface toward the other surface.