As explained above, according to embodiments of the present invention, by providing averaging section 111 that detects an average power value of amplitude component signals, and controlling transmission power based on the amount of drift in the average output power value of PA 103 and the amount of drift in the average power value of amplitude component signals, when residual drift components are included in the average output power value of PA 103, the influence of residual drift components can be eliminated and transmission power can be controlled, so that it is possible to improve the accuracy of transmission power control. That is, deterioration of power estimation accuracy resulting from residual drift components can be reduced, so that it is possible to satisfy the restrictive requirement that the difference between transmission power be within, for example, the range of +/−0.5 dB.