An optical scanning apparatus constructed to dispose optical elements guiding light beams to a deflector such as a rotary polygon mirror at a low cost with high accuracy, includes a first light source, a second light source, a deflector, a first optical member provided on a first optical path between the first light source and the deflector, a second optical member provided on a second optical path between the second light source and the deflector, and one wall holding both of a side surface of the first optical member and a side surface of the second optical member.