An image forming apparatus according to an example includes a main body, a driving coupler to drive a toner cartridge. The driving coupler is rotatable in a direction, a locking protrusion protrudes from an axial protrusion of the driving coupler in the direction of the driving shaft is lockable into a locking groove concavely formed in the direction of the driving shaft of a passive coupler of the toner cartridge. A driving force transmission surface of the axial protrusion of the driving coupler and a driving force receiving surface of the passive coupler are to contact each other to rotate the passive coupler in the direction.