Disclosed is an optical scanning device including a light source including
multiple light-emitting elements, the multiple light-emitting elements
being arranged in a linear manner, a collimator lens to collimate a light
beam from the light source, a light-deflecting device to deflect a light
beam having passed through the collimator lens to a medium to be scanned
and scan the medium with the light beam, and a rear optical system
arranged in an optical path between the collimator lens and the medium to
be scanned, wherein the collimator lens deviates an image surface in a
direction opposite to an image surface deviation on the medium to be
scanned by a nearly same amount as the image surface deviation, the image
surface deviation being caused by a change of an image height of the
light source, and the change being caused by the rear optical system.