An image forming apparatus includes an image carrier, a rotating brush, a collecting roller, a cleaning blade, a sealing member and a side sealing member. The sealing member has an extension part extending outside from each end of the collecting roller in an axial direction. The sealing member comes into contact with the collecting roller between a contact area between the rotating brush and the collecting roller and the cleaning blade and then prevents backflow of the residue. The side sealing member lifts the extension part toward the collecting roller on an outside at a predetermined interval from a position corresponding to each side edge of a maximum-width sheet passing region on the image carrier.