In a power supply circuit having input and output terminals, an error amplifier has first and second paths independent of each other to output a control voltage, a first MOS transistor is interposed between the input terminal and an intermediate node, and a step-up section steps up a voltage supplied from the intermediate node and outputs the stepped-up voltage to the output terminal. The step-up section includes a capacitor, a second MOS transistor, a third MOS transistor, and a drive circuit. The first end of the capacitor is connected to the intermediate node. The second MOS transistor is interposed between the input terminal and a second end of the capacitor. The third MOS transistor is interposed between the second end of the capacitor and a ground. The drive circuit drives the second and third MOS transistors in a complementary manner based on a clock signal.