When a connector of a power cord is connected to an inlet of a printer, an RFID reader of the printer acquires rating information of the power cord by reading the rating information from an RFID-IC of the power cord. Then, a controller of the printer judges whether the rating of the power cord conforms to the rating of the printer based on the rating information of the power cord and rating information of the printer. If it is judged that the rating of the power cord does not conform to the rating of the printer, the controller sets the printer to a sleep mode, in which the printer is operated with a current value within the rating range of the power cord, and also causes relevant parts of the printer such as an alarm generator to issue an alert/alarm to the operator.