Abstract: An optical scanning apparatus comprising a plurality of light sources, a polygon mirror for deflecting beams emitted from the light sources in a main scanning direction, lenses for imaging the deflected beams on receiving surfaces and diverting mirrors for directing the beams which passed through the lenses to the receiving surfaces. In one side of the polygon mirror, three diverting mirrors are provided in an upper optical path, and two diverting mirrors are provided in a lower optical path. In the other side of the polygon mirror, one diverting mirror is provided in a lower optical path, and two diverting mirrors are provided in an upper optical path. Thereby, bows on the receiving surfaces have the same curving direction, and color displacement can be inhibited.