An image forming apparatus includes attach/detach sections to/from each of which a developer container for containing developer can be attached/detached, and an image bearing body for bearing a latent image. When a developer container is attached to each of the attach/detach sections, the apparatus is usable as a color image forming apparatus. When a developer container is attached to only one of the attach/detach sections, the apparatus is usable as a single-color image forming apparatus. The image forming apparatus has a device ID that is sent to a computer when it communicates with the computer and that is used by the computer to recognize devices capable of communicating therewith. The device ID of the image forming apparatus for when it is being used as the color image forming apparatus matches the device ID of the image forming apparatus for when it is being used as the single-color image forming apparatus.