A power amplifier is smaller in size and limits input noise having a differential frequency. A power amplifier has an input terminal, an amplifying transistor, a bias circuit, a filter circuit, and an impedance matching circuit. The bias circuit supplies a bias to the signal input side of the amplifying transistor. The filter circuit removes noise at the signal input side of the amplifying transistor. The filter circuit has a matching resistor, a chip inductor, and a chip capacitor. Each of the chip inductor and the chip capacitor is a surface mount device. The matching resistor is located on a semiconductor substrate, has a first end connected to a connection point of two MIM capacitors, and a second end connected to a connection point of one of the MIM capacitors and the signal input side of the amplifying transistor.