An optical scanning apparatus includes an incidence optical system for causing a beam emitted from a light source to be incident on a deflector, and a scanning optical system for causing the beam reflected and deflected by the deflector to be imaged on a surface to be scanned. The scanning optical system has a first lens on the deflector side and a second lens on the surface to be scanned side. The first lens has positive power in the main scanning direction and has negative power in the sub scanning direction. The power of the first lens in the main scanning direction is greater than the power of the second lens in the main scanning direction, and the second lens has positive power in the sub scanning direction.