An image forming apparatus includes a housing; a process cartridge; and a protective member. The process cartridge is detachably attached to the housing and includes a drum unit; and a developing unit. The drum unit includes a photosensitive member. The developing unit includes a developing roller; and a first wall. The developing roller defines a first axis extending in an axial direction and is configured to rotate about the first axix. The first wall has a first surface; and a second surface opposite thereto. The first surface extends in the axial direction and faces the developing roller. The protective member is detachably attached to the process cartridge and includes a spacer. The drum unit includes a second wall. The second wall has a third surface. The third surface extends in the axial direction and faces the second surface. The spacer is disposed between the second surface and the third surface.