A sheet feeding procedure supplies recording media from a medium enclosing portion to a medium conveying path. An overlap-feed detecting procedure monitors a thickness of recording media supplied to the medium conveying path, thereby detecting the overlap-feed media. Sheet returning procedures (A) and (B) return the overlap-feed media into the medium enclosing portion when the overlap-feed media are detected. A looseness forming procedure applies rotational forces of different rotation speeds to upper and lower surfaces of the overlap-feed media during the medium returning procedure, thereby forming a looseness in the overlap-feed media. A medium re-feeding procedure supplies again the returned recording media to the medium conveying path from the medium enclosing portion. In the medium feed control, the overlap-feed can be further certainly recovered.