In an electronic device which can be energized from one of a plurality of types of power sources, having art external power source connector for connection with an external power source, a power source identifying circuit identifies the power source from which the electronic device is energized, and a control circuit controls consumption of the power in accordance with the power source identified by the power source identifying means. The identification of the power source is made in accordance with the voltage on the connector. Additionally, the sum of the voltage on the connector and the voltage of the built-in battery may be used for the identification.