After processing a medium B with a processing unit based on control data received from a host computer 92 and stopping conveyance of the medium B, the media processing device control unit 100 of a printer 1 prohibits processing the medium B by the processing unit, waits until displacement of the medium B is detected by a media orientation detection means 65, and reports starting to wait to the host computer 92. When displacement of the medium B is detected by the media orientation detection means 65 while waiting, the media processing device control unit 100 cuts the medium B with the automatic paper cutter 60, and then cancels prohibition of processing medium B by the processing unit.