To provide a developing unit 150 which can stop a developer D from sticking inside.

An air blowing nozzle 161 which blows air into a developer storage chamber 154 of the developing unit 150 is positioned. Then a toner in the developer D staying in the corners in the developer storage chamber 154 are dispersed with the air. Further, an agitating conveyor belt 157 which moves endlessly while carrying the developer on its surface with the influence of a magnetic force produced by a magnetic belt part 157a is used as an agitating conveyance member which agitates the developer D in the developer storage chamber 154. Then even the developer D which is left in the corners of the developer storage chamber 154 can be carried on the surface of the agitating conveyor belt 156.