In an operational amplifier, a control unit switches an operation mode between first and second operation modes. A first output drive stage circuit section is configured to amplify a first input signal differentially-amplified by a first or a second input differential stage circuit section to output as a first drive voltage, similar to a second output drive stage circuit section. First and second power supplies: supply voltages in a first voltage range to the first differential stage circuit section and the first output drive stage circuit section in the first operation mode, supply voltages in the first voltage range to the second differential stage circuit section and the first output drive stage circuit section in the second operation mode, similar to third and fourth power supplies. The drive voltage on each of the first and second output nodes is fed back.