This printer performs printing on a print medium having an RFID, and comprises: a communication unit which has a communication part movably provided in a predetermined area along the transport surface of the print medium, and communicates with an IC chip of the RFID; and a detection unit which detects the print medium by means of detection light. The detection unit includes: a light emitting part that emits detection light; a light guide member that guides the detection light emitted from the light emitting part to the print medium; and a light receiving part that receives the detection light via the print medium.