A power supply circuit includes first and second power supply circuits. The first power supply circuit has a first voltage generation circuit and the second power supply circuit has a second voltage generation circuit and an operational amplifier. When a load is in a low power consumption mode, only the first power supply circuit operates to output a first voltage to the load. When the load is in a normal operation mode, the second power supply circuit also operates to output a desired power supply voltage based on a reference voltage generated by the second voltage generation circuit. In this case, the operational amplifier controls not only the second power supply circuit but also the first power supply circuit. Thus, a desired power supply voltage is output to the load regardless of whether the first voltage is greater than the desired power supply voltage.