There is provided a charging power source apparatus by which quick charging can be carried out within a required range without imposing a burden on a secondary battery or a charging circuit. The charging power source apparatus is equipped with a plurality of control modes (e.g. normal charging mode and quick charging mode) for operating respectively with a plurality of output characteristics where the magnitudes of output currents being limited are different, and a detecting circuit for detecting a voltage appearing between the output terminals, and is configured such that one of the plurality of control modes is selected based on detection result from the detection circuit to perform an output operation.