An amplifying circuit comprising an output stage circuit composed of a first and a second output transistor and operating as a class AB push-pull circuit reduces electricity consumed by an idle current. A pre-stage circuit outputs a first and a second control signal, and controls a channel current of the first and the second output transistor. In a period in which one control signal causes the corresponding output transistor to operate in class AB mode, the other control signal places the corresponding output transistor in a cutoff state.