An image forming apparatus having a consumable detachably installed in the main body is disclosed. The image forming apparatus includes a main body having a first opening, a consumable which is detachably installed in the main body, a door mounted on the main body to open and close the first opening, and locking members operable in association with the movement of the door to secure the consumable in place as the door is closed. Possible damages due to the movement of the consumable such as a photosensitive cartridge during shipping and/or transporting of the image forming apparatus can be prevented by the locking members.