A toner cartridge includes: a body to contain toner and including a toner outlet to discharge the toner to the outside; an agitating member to rotate about a central axis of the body and agitate the toner contained in the body; a shutter member to move along the central axis with respect to the body, and having an open position to open the toner outlet and a blocked position to block the toner outlet; a driving force receiver exposed to the outside through the toner outlet when the shutter member is in the blocked position, and to rotate by receiving a driving force from the outside; and a driving shaft to transmit a rotational force of the driving force receiver to the agitating member.

An attached portion of an image forming apparatus includes a rotating member of which at least a part is exposed outside the image forming apparatus when the developer container is attached, and a rotation restricting mechanism that is movable between a restricting position to restrict rotation of the rotating member and an allowable position to allow rotation of the rotating member, and includes a restricting member that is at the restricting position when the developer container is not attached. The developer container is attached to the attached portion so that the discharging portion engaging portion and the shutter engaging portions are engaged with the frame engaged portions and the rotating member engaged portions respectively when the container shutter is in the close state, and the restricting member moves from the restricting position to the allowable position when the developer container is attached to the attached portion.

An attached portion of an image forming apparatus includes a rotating member of which at least a part is exposed outside the image forming apparatus when the developer container is attached, and a rotation restricting mechanism that is movable between a restricting position to restrict rotation of the rotating member and an allowable position to allow rotation of the rotating member, and includes a restricting member that is at the restricting position when the developer container is not attached. The developer container is attached to the attached portion so that the discharging portion engaging portion and the shutter engaging portions are engaged with the frame engaged portions and the rotating member engaged portions respectively when the container shutter is in the close state, and the restricting member moves from the restricting position to the allowable position when the developer container is attached to the attached portion.

An image forming apparatus includes: a body comprising a developing device, and a mounting unit from which a toner refill cartridge is detachable and which is connected to the developing device and delivers toner accommodated in the toner refill cartridge to the developing device. The body includes a housing having a communication hole so that the toner refill cartridge is mounted on the mounting unit from outside the image forming apparatus. The image forming apparatus includes a drive unit to provide a driving force to the toner refill cartridge so that toner is supplied from the toner refill cartridge to the developing device: a detecting unit to acquire a detected value corresponding to an amount of toner in the toner refill cartridge; and a controller to control an operation of the drive unit based on the detected value.