is to provide a radio frequency power amplifier of multi stage amplifying method that is designed to reduce instability of output power caused by electromagnetic coupling of bias supply terminals and interconnections of each stage to thereby operate stably another object of the present invention is to provide a radio frequency power amplifier that is designed to reduce distortion of output power caused by electromagnetic coupling of bias supply terminals and interconnections of each stage to thereby provide high efficiency the above objects can be achieved by providing a first interconnection connected to a terminal for supplying a voltage for collector driving to a power amplifying transistor a second interconnection connected to a terminal for supplying a voltage for collector driving to a second transistor controlling a base bias voltage of the above transistor and one or more ground parts for electromagnetic shield wherein the first interconnection and the second interconnection are separated by one or more of the ground parts for electromagnetic shield application_number US 348004 A description hereinafter the present invention will be described in more detail using preferred embodiments the accompanying drawings are used in the description to ease understanding of the present invention fig1 shows a configuration of a radio frequency power amplifier circuit in a first embodiment the radio frequency power amplifier circuit comprises an input impedance matching circuit 1 an input stage transistor 10 for power amplification an inter stage impedance matching circuit 2 an output stage transistor 11 for power amplifier an output impedance matching circuit 3 and a base bias voltage control circuit 20 for transistors 10 and 11 wherein the base bias voltage control circuit 20 in this circuit comprises the.