Provided is a developing device wherein a shutter can be smoothly opened/closed, and a toner can be prevented from leaking.
A developing device 1 is provided with a developing roller 2, a housing 3, a shutter 11, lock members 12A, 12B, and a cover 13. The housing 3 has a first opening 3B for receiving a toner. The shutter 11 can move between an opened position where the first opening 3B is opened, and a closed position where the first opening 3B is closed. The lock members 12A, 12B can move between a locked position where the shutter 11 is locked to the closed position, and a released position where the lock of the shutter 11 is released. The lock members 12A, 12B are positioned at the locked position when a toner cartridge 100 is removed from the developing device 1, and are moved to the released position from the locked position by being in contact with the toner cartridge 100 when the toner cartridge 100 is attached to the developing device 1. The cover 13 is positioned on the side opposite to the lock members 12A, 12B with respect to the shutter 11 in the attaching direction.