An optical scanning device includes a first aperture and an adjustment mechanism. The first aperture includes a first opening portion and a first cut portion. The first opening portion restricts a beam path width of a laser beam emitted from a light source. A first blocking member that blocks the laser beam is inserted in a detachable manner in the first cut portion in a direction perpendicular to a longitudinal direction of the first opening portion, at a predetermined position of the first cut portion. The adjustment mechanism is configured to adjust a fixed state of the first aperture.