Abstract: An electrophotographic apparatus is equipped with one or more printing sections including a photoreceptor, a charger that electrically charges the surface of the photoreceptor, an optical scanning section that optically scans the surface of the charged photoreceptor with a laser beam, a developer that develops image areas formed by optical scanning, a toner hopper that supplies toner to the developer, and an image transfer unit that transfers the developed image to a recording member. In this apparatus, the developer and toner hopper can be mounted and demounted separately and a plurality of toner hoppers and developers are changeable according to the kinds of toner colors to be used. Thus, of the developers and toner hoppers is equipped with a device that outputs electric signals to detect the correspondences of the toner hoppers and the developers.