A laser shutting device blocks laser beams in a laser scanning unit that includes a light source that emits laser beams and a beam deflecting unit that deflects the laser beams in a main-scanning direction and is adapted to form an image on a photosensitive body using the laser beams. The laser shutting device includes a shutter movably installed in a light path between the light source and the photosensitive body, an opening formed in the shutter that allows the laser beams to pass therethrough, and a laser shutting unit that moves the shutter using an electromagnet according to a start signal for operating the beam reflecting unit so that the laser beams can pass through the opening.