An optical scanning device has a light source comprising a plurality of light emitting points arranged on a plane two-dimensionally; a deflector for deflecting beams emitted from the light emitting points in a main-scanning direction; a first optical system for directing the beams emitted from the light emitting points to the deflector; and a second optical system for directing the beams deflected by the deflector to a photosensitive member and for imaging the beams on a surface of the photosensitive member. The plurality of light emitting points are arranged in a parallelogram lattice composed of M by N lattice points, wherein M and N are integers equal to or greater than six, with none of the light emitting points allocated on central (M−4) by (N−4) lattice points.