An optical scanning apparatus has first and second light sources, a deflection scanning device, and first and second scanning optical systems that guide the first and second laser beams deflected for scanning by the deflection scanning device. The first and second scanning optical systems include scanning lenses and a polarization beam splitter arranged in a downstream side of an optical path of the scanning lens, the first scanning optical system including a half-wave plate arranged in the downstream side of the optical path of the scanning lens and in an upstream side of an optical path of the polarization beam splitter, the first laser beam and the second laser beam having different phases by 180 degrees from each other before being incident on the first and second scanning optical systems.