An image forming apparatus includes an endless transfer member and a plurality of image forming units. The endless transfer member is arranged at a transverse position in the image forming apparatus, and has a circulatory rotating surface declining at a predetermined angle to a horizontal plane. Each of the plurality of image forming units includes a first surface facing the endless transfer member and a second surface opposite to the first surface and angled in a similar direction to the endless transfer member. The plurality of image forming units perform an image forming operation and are arranged next to one another facing the endless transfer member such that, in any two adjacent image forming units of the plurality of image forming units, one of the any two adjacent image forming units has a portion overhanging the other one of the any two adjacent image forming units.