Image forming apparatus

An image forming apparatus comprising:

• a main body casing having an opening and a drum guide;
• a cover movable between an open position in which the cover does not cover the opening and a closed position in which the cover covers the opening;
• a drum cartridge including a photosensitive drum rotatable about a first axis extending in a first direction, the drum cartridge being removably insertable into the main body casing through the opening in the first direction;
• a developing unit including a developing roller rotatable about a second axis extending in the first direction;
• and
• an intermediate transfer belt positioned above the drum cartridge and the developing unit in a state where the drum cartridge is attached to the main body casing;
• wherein in a case where the cover is in the open position, the developing roller is in a first developing position spaced from the photosensitive drum,
• wherein in a case where the cover moves to the closed position from the open position, the developing roller is moved toward the photosensitive drum from the first developing position,
• wherein the main body casing includes a protrusion,
• wherein the drum cartridge includes a groove,
• wherein the drum cartridge is movable relative to the main body casing from a first position in which the drum cartridge is in an inserting process to a second position in which the drum cartridge is attached to the main casing after the drum cartridge is inserted into the main body casing through the opening in the first direction, and
• wherein, in a case where the drum cartridge is at the second position, the protrusion of the main body casing is positioned within the groove of the drum cartridge.