An intermodulation distortion which is output from a final-stage amplifier 15 is fed back to an inter-stage matching circuit 14 via a first control circuit 16 and a second control circuit 17. The first control circuit 16 and the second control circuit 17 control an amplitude and a phase of an intermodulation distortion to be fed back from the final-stage amplifier 15 to the inter-stage matching circuit 14, such that a synthesized scalar of an intermodulation distortion input from a first-stage amplifier 13 to the final-stage amplifier 15 and amplified by the final-stage amplifier 15 and an intermodulation distortion newly generated by the final-stage amplifier 15 is reduced.