A high-frequency power amplifier has an FET element having a unit FETs in multifinger form, and having a gate pad through which a signal is input, a source pad that is grounded, and a drain pad through which a signal is output. A high-frequency processing circuit includes series resonance circuits shunt-connected between the gate pads of the unit FETs and grounding ends. Two of the series resonance circuits have respective different resonance frequencies which correspond to second and higher harmonics of a frequency included in the operating frequency band of the FET element.