An image forming apparatus includes an image bearing member; a developing device including a carrying member for carrying a one component developer and for developing an electrostatic image formed on the image bearing member with the developer; a rotatable developer supplying device, contacted to the carrying member, for supplying the developer to the carrying member; a developer regulating device for regulating an amount of the developer carried on the carrying member; a developer stirring device for stirring the developer a developer supply device for supplying the developer to the developing device; and a controller for controlling supply of the developer to the developing device from the developer supply device. A lower end of the developer stirring device is disposed at a position which is vertically above an upper end of the developer supplying device and which is vertically above a contact portion between the carrying member and the developer regulating device. A direction of rotation of the developer supplying device is such that the developer supplying device is contacted to the carrying member during a downward part of the rotation of the developer supplying device. The controller controls the developer supply device such that a lower limit of a height of a surface of the developer is vertically above a lower end of the developer stirring device and an upper limit of the height of the surface of the developer is vertically below a wall of an upper surface of the developing device.