A toner cartridge includes a first casing, a second casing, an auger screw, and a shutter. The first casing has a first internal space. The second casing has: a second internal space smaller than the first internal space; a first opening allowing toner in the second internal space to be discharged; and a second opening allowing air in the second internal space to be sent to an outside. The auger screw is rotatable about a first rotation axis and configured to convey toner in the first internal space to the second internal space. The shutter is rotatable relative to the second casing about a second rotation axis between a first position in which the shutter closes the first opening and a second position in which the shutter opens the first opening. In a state where the shutter is at the second position, the shutter does not close the second opening.