forming section 10 m to form magenta toner images includes charging device 2 m exposure device 3 m developing device 4 m first transfer roller 5 m and cleaning device 6 m all of which are arranged around drum shaped photo conductor 1 m image forming section 10 c to form cyan toner images includes charging device 2 c exposure device 3 c developing device 4 c first transfer roller 5 c and cleaning device 6 c all of which are arranged around drum shaped photo conductor 1 c image forming section 10 k to form black toner images includes charging device 2 k exposure device 3 k developing device 4 k first transfer roller 5 k and cleaning device 6 k all of which are arranged around drum shaped photo conductor 1 k intermediate transfer device unit 7 is structured of intermediate transfer device 70 being an endless belt which rotates as shown with an arrow in fig1 and rollers 71 72 73 and 74 intermediate transfer device 70 is an image carrier for carrying toner images which are to be transferred onto transfer material s image forming sections 10 y 10 m 10 c and 10 k are image forming devices for forming toner images onto intermediate transfer device 70 unicolor toner images each formed by image forming sections 10.