An image forming apparatus includes a rotatable image bearing member bearing an electrostatic image; a rotatable developer carrying member carrying a developer to develop the electrostatic image; speed controlling means for switching a rotating speed of the image bearing member between a first speed and a second speed lower than the first speed, and performing an image forming operation at each speed; and developer carrying member speed controlling means for controlling a rotating speed of the developer carrying member so that a rotating speed of the developer carrying member when the image forming operation is performed by rotating the image bearing member at the second speed, which is less than 70% of the first speed so as to be within a range of .+-.30% of a rotating speed of the developer carrying member when the image forming operation is performed by rotating the image bearing member at the first speed.