A photodetection device includes: a photoelectric converter generating charge; a first diffusion region having a first end connected to the photoelectric converter and a second end and extending in a first direction from the first end toward the second end; a second diffusion region having a third end connected to a first side surface, of the first diffusion region, which is along the first direction and a fourth end and extending in a second direction from the third end toward the fourth end; a first charge accumulator connected to the fourth end; a first gate electrode covering at least part of the first diffusion region; and a second gate electrode covering at least part of the second diffusion region. The second gate electrode covers a first portion of the first diffusion region without the first gate electrode intervention. The first portion is adjacent to the second diffusion region.