next the image formation unit 60 integral assembly of transfer frame 30 intermediary transfer belt unit 20 process cartridges 15 and image formation station housing 50 which supports preceding components is to be pulled out frontward of the main assembly that is in the direction indicated by an arrow mark p 2 as shown in fig6 b next referring to fig7 the integral combination of the intermediary transfer belt unit 20 and transfer frame 30 is to be rotated about the rotational shaft 30 e in the direction indicated by an arrow mark q 2 to cause the combination to be held upright by a holding means such as a damper by this operation the process cartridges 15 mounted in the image formation station housing 50 are exposed from behind the intermediary transfer belt unit 20 making it possible to replace the process cartridges 15 in other words the space necessary to mount or remove the process cartridge 15 is provided thus the process cartridges 15 can be pulled out upward indicated by arrow mark t 1 to be replaced in other words the intermediary transfer belt unit 20 is rotated away from or rotated to the image formation station housing 50.