Provided is an optical scanning apparatus, including: an optical deflector having a polygon mirror reflecting a light flux emitted from a light source to carry out scanning, a drive unit rotating the polygon mirror about a rotation shaft, and a board supporting the drive unit; an optical box to which the board is fixed; two holes provided in the optical box, through which two screws fixing the board are inserted, respectively; two bearing surfaces provided on the optical box at positions around the two holes, respectively, the two bearing surfaces supporting the board; and an abutment portion provided on the optical box and abutting against a portion that is prevented from being pressed by the two screws in the board which is sandwiched between the two screws and the two bearing surfaces so as to be fixed to the optical box.