A multi-beam scanning apparatus includes a light source having first and second light source sections that hold a pair of semi-conductor laser diodes and coupling lenses that couple four beams irradiated from the pair of semi-conductor laser diodes with a base member. A light beam deviating device may be provided so as to deviate the four beams. A scan imaging device is also provided so as to scan a scan receiving surface with beam spots of the beams deviated by the light beam deviating device. A beam pitch-detecting device is also provided so as to detect a beam pitch of the respective beams formed on the scan-receiving surface. A beam pitch correcting device is provided in order to correct the beam pitch by causing relative deviation of a light axis among the respective beams on a sub scanning direction cross sectional plane.