An object of the present invention 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.