An optical scanning apparatus includes first and second light source units including respective light sources; a rotating polygon mirror that performs deflection scanning of laser beams emitted from the light sources included in the first and second light source units; and a positioning member including a first abutting portion on which the first light source unit abuts and a second abutting portion on which the second light source unit abuts, the positioning member positioning the first and second light source units. The first and second light source units are positioned by the positioning member and arranged next to each other in a rotation axis direction of the rotating polygon mirror. The positioning member is a single member disposed between the first and second light source units in the rotation axis direction.