A contact type image transferring device and method incorporated in an image forming apparatus for cleaning a residual toner on a transfer roller. The transfer roller is in contact with a photoconductive drum at a first force and forms nip between the roller and the drum. A sheet of paper passes through the nip and a toner image on the drum is transferred to the sheet of paper. When the sheet of paper is not at the nip, the transfer roller is moved such that the force of the roller against the drum is a second force which is different from the first force. A cleaning bias voltage is applied to the roller and toner on the roller is transferred to the drum.