The image forming apparatus includes first and second developing apparatuses for developing electrostatic images on first and second image bearing members, a first developer container containing a developer, first supplying device for supplying the developer in the first developer container to the first developing apparatus, a second developer container containing a developer to be supplied to the second developing apparatus, second supplying device for supplying the developer in the second developer container to the second developing apparatus, driving device for driving the first and second supplying device, changeover device which changes over the driving force of the driving device during one image forming operation to first and second states in which the driving force is respectively transmitted to each of the first and second supplying device, and control device for changing the times of the first and second states according to a condition of an image to be formed.