An image forming apparatus includes at least one image forming unit configured to form an image, a belt for transferring an image formed by the image forming unit onto a recording material, and an opening and closing unit having the belt and openable and closable relative to a main body of the apparatus. The belt is provided above the image forming unit, and the image forming unit is removable from the main body of the apparatus when the opening and closing unit is open. The opening and closing unit slides substantially horizontally, thereby opening and closing relative to the main body of the apparatus.