An image forming device includes a plurality of image forming units provided in parallel comprising a black image forming unit to form a black toner image and a plurality of color image forming units to form color toner images, an intermediate transfer device to primarily transfer color toner images formed by superimposing the toner images formed at each image forming unit, and a secondary transfer unit to transfer the color toner image to a transfer paper. The color image forming unit employs a non-magnetic-contact-type single-component development device to develop each color toner image with a single-component developer, and the black image forming unit is provided closest to the secondary transfer unit and employs a contact-type two-component development device to develop a black toner image with a two-component developer.