A developing apparatus and an image forming apparatus

A developing apparatus comprises a magnet roller (45) for supplying a developing agent consisting of toner and a carrier to a portion to be developed, an upper screw (42) opposed to the magnet roller (45), for stirring/transporting the developing agent in a first direction, and a lower screw (43) provided below the upper screw (42) in parallel with the upper screw (42), for receiving/transporting the developing agent from/to the upper screw (42) and for sending the developing agent to the magnet roller (45), while stirring/transporting the developing agent in a second direction opposite to the first direction. The magnet roller (45) includes a supply portion (45a) having a plurality of magnetic poles (53a to 53e) arranged in a first magnetic pole arrangement, for supplying the developing agent to the portion to be developed, and a transport portion (45b) having a plurality of magnetic poles (55a to 55e) arranged in a second magnetic pole arrangement different from the first magnetic pole arrangement, for transporting the developing agent transported by the lower screw (43), to the upper screw (42).