Disclosed is an electromagnetic-inductive power supply apparatus, which switches so that a plurality of coils winding around a current transformer core is connected in series to a rectification unit based on the voltage induced in the current transformer, thereby producing the power within the set range even in a state where the voltage outside the reference is induced. The disclosed electromagnetic-inductive power supply apparatus senses the voltage induced in the current transformer and switches the plurality of unit coils is connected to the rectification unit based on the voltage sensed.