A joint member moves forward and backward between an advanced position and a retracted position according to the rotation of a rotary member when a cover is opened and closed between an open state and a half open state, and rotates at the advanced position according to the rotation of the rotary member when the cover is opened and closed between the half open state and a closed state. A coupling member is engaged with the joint member when the joint member is at the advanced position while being disengaged from the joint member when the joint member is at the retracted position. The coupling member opens and closes a toner supply port by rotating according to the rotation of the joint member engaged therewith at the advanced position.