body 1 in the main body 1 there are an aligning roller pair 4 to align paper p a conveyer belt 5 to convey paper p a fixing device 6 to fix an image on paper p and an exit roller pair 7 to exit paper p having a fixed image are provided in order along the conveying direction of paper p the conveyor belt 5 is manufactured by for instance semiconductive polyimide and has a characteristic stabilized from the viewpoint of thermal as well as abrasion resistance the conveyor belt 5 is put between a driving roller 8 and a driven roller 9 the driven roller 9 is given with a tension so that the conveyor belt 5 travels without being loosened above the conveyor belt 5 there are process units 10 y 10 m 10 c and 10 b provided in the conveying direction of paper p yellow magenta cyan and black toners are used in the process units 10 y 10 m 10 c and 10 b respectively each of the process units 10 y 10 m 10 c and 10 b is provided with a photosensitive drum 15 and around this photosensitive drum 15 there are a main charger 16 a optical laser beam unit 17 a developing device 18 and a cleaning device 19 arranged in order along the rotating direction of the photosensitive drum at.