A pulse electric power amplification apparatus includes first, second, final-stage and drive amplification devices. In initial stage, the first device in upstream, having a predetermined thermal time constant, receives a high frequency signal while the second device in downstream, having a different thermal time constant, is cascade-connected to it. In final stage, the drive device drives the final-stage device in downstream, which is cascade-connected to the second device. The apparatus further includes a power supply switching circuit, first and second differentiating circuits. The first and second differentiating circuits, having time constants corresponding to thermal time constants of the first and second devices, respectively, receive a pulse signal with which the high frequency signal is modulated. The power supply switching circuit, also receiving the pulse signal, switches a voltage outputted from a positive bias power supply and inputs the switched voltage to the first, second, drive and final-stage devices.