To attain highly accurate identification of power-supply to be used.

This appliance is provided with power terminals 1a, 1b for its main body which is formed so that its power from either of a battery 3 or constant-voltage power supply 4 may be supplied in common, and an identifying means 2 which identifies which has generated the power supplied to the power terminals 1a, 1b of the main body, the battery 3 or the constant-voltage power supply 4 by power voltage supplied to the power terminals 1a, 1b of the main body. The identifying means 2 identifies which has generated the power, the battery 3 or the constant-voltage power supply 4, according to the voltage of the power terminals 1a, 1b of the main body before the main body is driven, and controls driving of the main body of the portable electronic appliance according to which has generated available power, the battery 3 or the constant-voltage power supply 4.