Provided is an optical scanning apparatus for optically scanning a surface
to be scanned, including: a light source unit that emits a beam modulated according
to an image signal; a condenser lens for temporarily focusing the beam emitted
from the light source unit into an image in a sub-scanning section in the vicinity
of a deflection surface of a light deflector; and a scanning optical system for
guiding the beam deflected by the light deflector onto the surface to be scanned,
in which: in the sub-scanning section, the beam from the condenser lens is incident
at an angle with a normal to the deflection surface; and an scanning optical element
constituting the scanning optical system has an optical axis eccentric toward a
deflection point side of the deflection surface with respect to a transmission
position of a principle ray of the beam in a sub scanning direction.