1. An image forming apparatus comprising: an image bearing member; a charging member for contacting a peripheral surface of said image bearing member to electrically charge the peripheral surface; a first developing device for forming a first developed image on the peripheral surface of said image bearing member charged by said charging member; a second developing device for forming a second developed image on the peripheral surface, wherein a combined developed image is formed by superimposing the first developed image and the second developed image on a common transfer material, wherein when the combined image is formed, said charging member is cleaned by transferring material deposited on said charging member to a region between said first developed image and said second developed image on the peripheral surface of said image bearing member, and wherein said first developed image or said second developed image is not formed in the region.