When an output of an overall output terminal (18) of a power supply circuit (10) is switched from a series regulator section (14) to a switching regulator section (12), a fifth switch (55) is switched OFF, to temporarily open a feedback loop of the switching regulator section (12), a sixth switch (56) is maintained at an ON state, to output the output of the series regulator section (14) to the overall output terminal (18), and an artificial feedback loop is formed between an output terminal of an error amplifier (24) and a second terminal of the error amplifier (24), to output a voltage corresponding to the output of the series regulator section (14) to the output terminal of the error amplifier (24) and charge a phase compensating capacitor (26) of the switching regulator section (12).