An illumination lens applies a laser beam emitted from a laser light source onto a light valve. The laser beam divided into a number of beams and modulated in the light valve is reflected by a total internal reflection prism so that the optical path thereof is bent, and thereafter passes through a zoom lens to be focused on a recording medium mounted on the surface of a drum. At this time, an image of a single pixel is recorded with a plurality of adjacent laser beams in a subscanning direction (direction of arrangement of the laser beams). The image can be recorded on the recording medium with sufficient power density.