An image forming apparatus includes: an image bearing body on which surface an image is formed and borne; an image forming section that forms the image; a transfer device that transfers the formed image to a transferring body; a cleaning member that comes into contact with the surface of the image bearing body to scrape an adhesion substance after the image is transferred; a storage tank in which the removed adhesion substance is stored; a damming member that obstructs a region between the cleaning member and the storage tank to temporarily dam the adhesion substance moving from the cleaning member to the storage tank on the cleaning member side, the damming member including overlapped members having openings, the members including a movable member that is slidable with respect to other member; and a driving section that drives the movable member to change an overlapping amount between the openings.