An image forming apparatus and corresponding method, the apparatus including at least one image bearing member configured to bear an image, an intermediate transfer member configured to transfer the image formed on the at least one image bearing member, a roller configured to support the intermediate transfer member with tension, a cleaning unit disposed opposite to the roller and configured to remove residual toner from the intermediate transfer member, and is detachably disposed opposite to the roller, a holder configured to accommodate the roller, and a positioning member detachably mounted on the holder and configured to position the cleaning unit to a positioning reference.