An optical printer using laser beams, wherein, when a plurality (n) of laser beams are used at once to carry out a scanning operation, the positions of spots of said laser beams in both the primary scanning direction and sub-scanning direction are set so as to have the relation l=(n-1)a+m.multidot.n.multidot.a, wherein m is a positive integer (m.gtoreq.1); a the distance between the adjacent scanning lines in the sub-scanning direction on the printing surface of the optical printer after a printing operation; and l the distance between the adjacent laser beams in the sub-scanning direction on the surface of a photosensitive drum, whereby a high-quality printing effecting no overlapping and omission of images can be obtained even if the distance between the adjacent laser beams is increased during a scanning operation using a plurality of laser beams at once.