PURPOSE: To obtain excellent lighting with simple constitution without requiring any extra mechanism by exposing a no-image part through an unmagnification image forming lens system which is not used during the variable power being applied.

CONSTITUTION: A lens system 6 is put on a projection optical path during unmagnification image formation, and a lens system 7 is put off the optical path; and luminous flux passed through the notched part 5a of a reflecting umbrella is prevented by a light shield plate 9 from reaching a photosensitive drum 1. The lens system 6 for unmagnification image formation is put off the optical path and the lens system 7 for reduction image formation is placed on the projection during reduction image formation; and the lens system 6 is moved to where lunimous flux from the notched part 5a of the reflecting umbrella is guided onto the photosensitive drum 1. A shutter 10 is provided between a platen 3 and a compound eye lens system and opened and closed associatively with the movement of the platen 3 to eliminate an unexposed part. The shutter 10 is displaced out of the optical path on the start of copying to prevent effective luminous flux from being cut off.