A radio frequency signal RF is input to a base of each of transistors TR1 through TRn via a corresponding capacitor among capacitors C1 through Cn, is amplified, and is output from a collector of each of the transistors TR1 through TRn. An emitter of each of the transistors TR1 through TRn is grounded. A bias voltage DC given from a bias circuit Bias is supplied to the base of each of the transistors TR1 through TRn via a corresponding resistor among resistors Ra1 through Ran. A signal line for the bias voltage DC is connected to an input line for the radio frequency signal RF via the bridge resistor R in a direct current manner.