The present disclosure features an image forming apparatus having a first developing unit having a first developing roller; and a first toner supply unit configured to supply toner to the first developing unit, the first toner supply unit having: a first container configured to accommodate the toner therein, the first container having a first inlet opening through which the toner is received in the first container and a first outlet opening through which the toner in the first container is discharged; a first lid configured to close the first inlet opening; and a first shutter configured to open the first outlet opening when the first lid closes the first inlet opening, and to close the first outlet opening when the first lid opens the first inlet opening.