PURPOSE: To enable the imaging magnification in the longitudinal direction of a slit and the short side direction of the slit by disposing auxiliary projecting optical systems in the optical path of a main projecting optical system.

CONSTITUTION: Auxiliary lens systems 8, 9 having an anamorphic imaging characteristic are disposed on the outside of the optical path in the 1st state and therefore the original on platen glass 1 is illuminated by a device consisting of a lamp 3 and an auxiliary reflecting mirror. The image is then formed via a slit 2, a mirror 4, a main projecting zoom lens system 5 for a rotating object and a mirror 6 onto a photosensitive drum 7. Such image has the equal imaging magnification in both the orthogonal longitudinal and short side directions of the slit. The systems 8, 9 are inserted in the optical path in the 2nd state and therefore the imaging magnification in both directions varies. The original and the photosensitive drum are optically conjugatively held in both orthogonal directions.