Power supply for charging

A power supply for charging 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 power supply for charging has such output characteristics that the magnitude of output current is limited when the load resistor is small. The power supply for charging 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 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 results from the detection circuit to perform an output operation.