A bias voltage is applied via a first resistance to the base of a first transistor, and a radio frequency signal is input via a first capacitor to the base of the first transistor. The bias voltage is applied via a second resistance to the base of a second transistor. The bias voltage is applied via a third resistance to the base of a third transistor, and the radio frequency signal RF is input via a third capacitor to the base of the third transistor. A first band rejection filter is provided between the base of the first transistor and the base of the second transistor. A second band rejection filter is provided between the base of the second transistor and the base of the third transistor. The collectors of the first to third transistors are connected in common and the emitters thereof are all grounded.