An image forming apparatus that has improved usability, while maintaining good positional relationship of units detachably installed inside the apparatus body. The image forming apparatus includes a plurality of rotatable image carriers, each incorporated in a respective image producing unit, and an intermediate transfer unit including an intermediate transfer body which is installed between a plurality of roller members and to which transfer toner images formed on each image carrier are transferred. The shaft of each image carrier and the shaft of each roller are disposed on a positioning plate, and each image carrier and the intermediate transfer body are fixed in normal positions by applying pressure independently to each shaft.