PURPOSE: To exercise invariably stable, precise image adjustment control by utilizing the shutter plate of the original exposure part of an automatic original conveyor as the reference surface of a formed-image adjustment control system for an adequate image in an image formation device.

CONSTITUTION: A shutter plate 413 prevents an image of a gripper 407, gripping the front edges of an original, from appearing on a copy when the gripper is illuminated at an exposure part E, and the shutter plate 413 is arranged between a drum 408 and a glass plate 410 so that it slides in the tangential direction of the drum. This shutter plate 413 is further used as the reference surface member of a formed-image adjustment control system; when the shutter plate 413 is closed, a light source 414 is turned on to expose the external surface of the shutter plate 413, the photosensitive drum surface is exposed to the reflected light through a mirror 419, and its latent image potential is detected by a sensor and then fed back to the formed-image adjustment control system.