An image forming apparatus includes a casing including a first side frame, a second side frame, and an opening, a cartridge configured to be attached to and removed from the casing through the opening, and an openable member configured to open and close the opening. A first side and a second side of the cartridge are supported by the first side frame and the second side frame, respectively, when the cartridge is attached to the casing. A part of the cartridge attached to the casing protrudes in a removal direction of the cartridge relative to an end of each of the first side frame and the second side frame in the removal direction. The openable member includes a wall portion. When the openable member closes the opening, the wall portion of the openable member is spaced apart in the removal direction from the part of the cartridge attached to the casing.