A photoelectric conversion device includes: a pixel region in which pixels each including a photoelectric converter is arranged, and micro-lenses corresponding to the pixels. The pixel region includes adjacent first and second regions, a first pixel in the first region and a second pixel in the second region adjacent in a direction in which the first and second regions are aligned are arranged at a first arrangement pitch, two pixels in the first region adjacent in the direction are arranged at a second arrangement pitch, two pixels in the second region adjacent in the direction are arranged at a third arrangement pitch, the second and third arrangement pitches are smaller than the first arrangement pitch, and an arrangement pitch of two micro-lenses corresponding to the pixel in the first regions and the pixel in the second region that are adjacent is smaller than the first arrangement pitch.