A photogate electrode has a planar shape of a rectangular shape having first and second long sides opposed to each other and first and second short sides opposed to each other. First and second semiconductor regions are arranged opposite to each other with the photogate electrode in between in a direction in which the first and second long sides are opposed. Third semiconductor regions are arranged opposite to each other with the photogate electrode in between in a direction in which the first and second short sides are opposed. The third semiconductor regions make a potential on the sides of the first and second short sides higher than a potential in a region located between the first and second semiconductor regions in a region immediately below the photogate electrode.