Image forming apparatus including coupling member selectively coupled to photosensitive drum

An image forming apparatus comprising:

• a main casing;
• a process frame movable into and out of the main casing in a front-to-rear direction;
• and a plurality of process cartridges supported by the process frame, the plurality of process cartridges being movable together with the process frame relative to the main casing in a state where the plurality of process cartridges is supported by the process frame,
• one of the plurality of process cartridges including:
• a drum cartridge movable relative to the process frame in a gravitational direction, the drum cartridge including a photosensitive drum rotatable about a drum axis extending in a left-right direction, the left-right direction crossing both of the front-to-rear direction and the gravitational direction;
• and
• a toner cartridge configured to accommodate toner to be supplied to the photosensitive drum, the toner cartridge being removable relative to the process frame in the gravitational direction.