A high-frequency power amplifier of the present invention comprises a power supply unit for including a transistor for switching whose drain electrode—source electrode or collector electrode—emitter electrode are on/off controlled according to a pulse signal corresponding to an envelope signal of a high-frequency signal applied to a gate electrode or to a base electrode, and for generating a voltage corresponding to the envelope signal by means of on/off operation of the transistor for switching; and a transistor for power amplification which is a source electrode grounded type or an emitter electrode grounded type, to which a voltage generated by the power supply unit is supplied as an operating voltage, in which the high-frequency signal is applied to the gate electrode or to the base electrode. Further, the transistor for switching in the power supply unit and the transistor for power amplification are arranged so that the source electrodes or the emitter electrodes are commonly connected in one package.