An image forming apparatus, which has a plurality of image forming units, comprises a plurality of cartridges adapted to supply developer; a plurality of supply members adapted to supply developer to the image forming units from a plurality of the cartridges; a drive unit adapted to drive a plurality of the supply members; and a control unit adapted to supply developer from a plurality of the cartridges by selectively operating a plurality of the supply members based on the amount of developer accommodated in the cartridges.