The image forming apparatus comprises: a first photosensitive drum; a second photosensitive drum; deflective scanning means for deflecting a laser beam and scanning by rotation; first laser irradiation means including a plurality of light emitting sources of laser beam for irradiating the first photosensitive drum, to irradiate the deflective scanning means with the laser; second laser irradiation means including a plurality of light emitting sources of laser for irradiating the second photosensitive drum, to irradiate the deflective scanning means with the laser beams; supporting means for supporting the first laser irradiation means and the second laser irradiation means; and a rotation supporting member for rotationally moving the first laser irradiation means, the second laser irradiation means and the supporting means integrally with respect to an axis generally parallel to the emanating axis of the laser beam to be emitted from the first laser irradiation means.