Imaging Device having a Diffusion Region Electrically Connected to a Photoelectric Converter and Overlapping a Region Penetrating another Region of Opposite Conductivity

An imaging device includes a semiconductor substrate and a pixel. The semiconductor substrate includes first and second surfaces that oppose each other, a first region containing an impurity of a first conductivity type, a second region that contains an impurity of a second conductivity type and that is closer to the first surface than the first region is, a third region that contains an impurity of the first conductivity type and that is closer to the first surface than the second region is, and a fourth region that provides connection between the first and third regions and that contains an impurity of the first conductivity type. The pixel includes a photoelectric converter, and a first diffusion region that is electrically connected to the photoelectric converter, that is located in the third region, that is exposed at the first surface, and that overlaps the entire first diffusion region in plan view.