A optical scanning apparatus includes a surface emitting type laser diode, a collimator lens which converts the emitted laser beam into an substantially parallel laser beam, a stop member which shapes the substantially parallel laser beam into a desired shape, a polygon mirror which deflects and scans the shaped laser beam, an electro-optical crystal member which is provided in the optical path between the stop member and the polygon mirror, and deflects the shaped laser beam by an applied voltage, a light amount sensor which detects the amount of laser beam deflected by the electro-optical crystal member, and a light amount control unit which controls the amount of laser beam emitted from the laser diode while repeatedly comparing the detected light amount obtained from the light amount sensor with a light amount corresponding to a reference voltage for control light amount.