An image forming apparatus includes an image bearing member on which an electrostatic image is formed; a developing device for developing the electrostatic image formed on the image bearing member with a developer including toner and a carrier; a supplying apparatus for supplying into the developing device a supply developer including toner by rotating a feeding screw; inclination detecting means for detecting an inclination of the feeding screw; and control means for controlling rotation of the feeding screw on the basis of a result of detection of the inclination detecting means.