A toner cartridge, a main casing accommodates therein toner and is formed with an opening which provides communication between an interior and an exterior of the main casing. A shutter is movable along the main casing by an external driving force applied in a force direction between a closed position at which the shutter closes the opening and an open position at which the shutter opens the opening. A toner seal is formed with a seal opening opposing the opening of the main casing, and interposed between the main casing and the shutter when the shutter is positioned at the closed position. A guide portion is configured to guide a movement of the shutter in an inclined direction inclined with respect to the force direction.