Abstract: Emission windows are prevented from being contaminated and are cleaned easily. The emission windows for emitting light beams are disposed on a housing of a laser exposure device having optical elements arranged inside for exposing a photoreceptor, and the upper surface of the housing is provided with a slidable shutter with openings. An image forming apparatus includes guide rails independent of the laser exposure device to movably guide predetermined cleaning brushes in the longitudinal direction of the emission windows. When the cleaning brushes are mounted on the guide rails and moved toward the inner side of the apparatus, the cleaning brushes touch a slant portion of a rib and the shutter is moved to the right to align the openings with the emission windows. While the cleaning brushes touch a longitudinally extending portion, the emission windows are exposed to enable the cleaning of the exposed window using the cleaning tool.