An image forming apparatus includes a substantially horizontally arranged image bearing member; a developing unit, including a plurality of developing devices and supporting the developing devices rotatably relative to the image bearing member; a movable intermediate transfer belt supported by first and second rotation members and facing the developing unit; a primary transfer member forming, together with the image bearing member, a primary transfer portion located near the first rotation member in a moving direction of the intermediate transfer belt, through the intermediate transfer belt; and a secondary transfer member forming, together with the second rotation member, a secondary transfer portion through the intermediate transfer belt. A toner image formed on the image bearing member by the developing unit is transferred on the intermediate transfer belt at the primary transfer portion, and is transferred on a recording material at the secondary transfer portion.