A photoelectric conversion device includes a plurality of light receiving elements, a plurality of A/D conversion units, and an offset giving unit. The light receiving elements are arrayed in one direction and each convert a light signal into an electrical signal. The A/D conversion units perform A/D conversion on the electrical signals output from the light receiving elements. The offset giving unit gives an offset voltage of a certain level to the electrical signals output from the light receiving elements without flowing a steady current before the electrical signals are input into the A/D conversion units.