A substrate including a first surface and a second surface, a first region of a first conductivity type disposed at a first depth, a second region of the first conductivity type disposed at the first depth and separated from the first region, a third region of the first conductivity type disposed at a second depth shallower than the first depth, a first gate, a second gate, a third gate, and a microlens disposed such that transmitted light is incident on the first region, the second region, and the third region. Signal charges accumulated in the first region are read out through the third region and an impurity concentration of each of the first region and the second region is lower than an impurity concentration of the third region.