To eliminate the need of making a bias/power supply voltage control system which is needed to cope with the changing speed of an envelope have a complicated circuit configuration to cope with a high-speed envelope change (high-speed communication) due to the slow speed of the transient response of an ordinary power system when the system controls the bias/power supply voltage supplied to a power amplifier by detecting the envelope.

In order to change the operating point of the power amplifier at the forefront of the slot of transmitted signals according to the transmission power 108 of transmitting signals, the transmission power is controlled in the cycle of the slot by calculating the bias by means of a bias calculating section 111 and controlling the timing by means of a timing control section 112.