An image forming apparatus includes: an image forming apparatus body, a photosensitive member, an intermediate transfer belt, and a developing device placed on a side opposite to the intermediate transfer belt across the photosensitive member and provided with a detachable toner cartridge. The intermediate transfer belt is disposed such that a distance between ends in a height direction is longer than a distance between ends in an anteroposterior direction. At least a part of the photosensitive member is placed between the anteroposterior ends of the intermediate transfer belt. The image forming apparatus body includes an openable section at an upper face side or a front face side thereof to allow the toner cartridge to be attached and detached therethrough and to allow a jam to be fixed therethrough.