PURPOSE: To reduce excessive moisture adsorption to the surface of a photosensitive body, which is a factor of a picture flow, and to raise environmental stability by installing a dehumidifying member in the vicinity of the surface of an image carrier body, and providing a drying means of the dehumidifying member.

CONSTITUTION: An amorphous silicon photosensitive drum is set to a commercially available copying device serving as an image forming device. A silica gel plate 4 seving as a dehumidifying member, which has almost the same curvature as a photosensitive drum 1 and has size of 300mm length × 30mm width × 5mm thickness is set so as to maintain an interval of 5mm to the surface of the drum, in a space extending from a transfer material separating roller 2 to a cleaning device 3, an air lead-in pipe 6 having a manifold type nozzle 5 is provided in the vicinity of the back face of the plate concerned, and it is connected to a small- sized hot air device 8 serving as a drying device set to other part in the copying device through a pipe 7 made of polyethylene. A picture flow is prevented by reducing only humidity in the vicinity of the photosensitive body by the dehumidifying member 4.