A photoelectric conversion device includes: a first substrate of which end portions are cut off so as to slope or with a groove shape; a photodiode and an amplifier circuit over the first substrate; a first electrode electrically connected to the photodiode and provided over one end portion of the first substrate; a second electrode electrically connected to the amplifier circuit and provided over an another end portion of the first substrate; and a second substrate having third and fourth electrodes thereon. The first and second electrodes are attached to the third and fourth electrodes, respectively, with a conductive material provided not only at the surfaces of the first, second, third, and fourth electrodes facing each other but also at the side surfaces of the first and second electrodes to increase the adhesiveness between a photoelectric conversion device and a member on which the photoelectric conversion device is mounted.