An image forming apparatus includes: image forming units provided detachably and each having a developing roller for supplying a toner to an electrostatic latent image formed on a charged photoconductor drum to form the electrostatic latent image into a visible image; an endless intermediate transfer belt which is provided in such a manner as to be capable of abutting against the photoconductor drum and is adapted to rotate in loop form by being supported in a tension-adjusted state by a plurality of rollers, and onto which a toner image developed on the photoconductor drum is transferred; and a high-voltage unit which is electrically and mechanically connected to the image forming units through terminals to supply predetermined electric power to the photoconductor drums, chargers, and the developing rollers of the image forming units. The image forming units are arranged to be moved in a width wise direction of the intermediate transfer belt so as to be connected to the high-voltage unit.