An optical writing device includes a light source, an optical deflector that deflects and scans light from the light source, a pre-deflector optical system that guides the light from the light source to the deflector, a post-deflector optical system that guides the scanned light to a target surface, a cover covering the deflector and including a first opening and a second opening provided at different positions, and a housing housing these optical elements. Light traveling from the light source to the deflector and the light scanned by the deflector are transmitted through the first opening but not through the second opening. During the rotation of the deflector, a forced inflow of air flowing from outside to inside the cover is generated in the first opening, and a discharged airflow flowing from inside to outside the cover is generated in the second opening.