PURPOSE: To prevent developing powder from scattering even in the middle of handling a developing powder supply device by providing a stop device for stopping a replenishing roller at a position where a supply groove is not exposed to the outside in a supply opening part.

CONSTITUTION: The replenishing roller 55 of the developing powder supply device 28 is rotated by a driving device 78 with a replenishment commanding signal. The developing powder which gets in the supply groove 57 on the peripheral surface of the replenishing roller 55 drops at the supply opening part 54 to be replenished in a developing device 3. After specified time elapse or when the driving device 78 is stopped with a stopping signal, the stop device 81 is actuated to surely stop the replenishing roller 55 at a position where all the grooves 57 of the roller 55 are not exposed in the supply opening part 54. Thus, the developing powder is prevented from scattering even in the middle of handling the developing powder supply device.