PURPOSE: To improve reliability and to reduce fitting space by cutting off exposure projection light to a photosensitive drum by a shutter part composed of many segments which transmit and cut off light individually under the control of an electric signal such as a liquid crystal shutter.

CONSTITUTION: The liquid crystal shutter 13 is installed nearby the photosensitive drum 9 where projection light 5 is cut off. This liquid crystal shutter 13 is composed of many liquid crystal segments, which transmit and cut off light according to the electric signal SS from the control part 14 consisting of a cpu 14a and a liquid crystal driver 16b. When the entire surface of the liquid crystal shutter 13 is placed in a light shield state with the electric signal SS of the control part 14, the projection light 5 is cut off by the liquid crystal shutter 13 and the drum is not exposed. When a transparent part in slit-shaped pattern is formed on the liquid crystal shutter 13 with the electric signal SS from the control part 14, the projection light 5 illuminates the photosensitive drum 9 through the transparent part to form an electrostatic latent image on the photosensitive drum 9.