Ideal nonlinear distortion compensation is realized by removing an imperfection of amplitude delay characteristic and an affection of inherent deviation that an amplifier has. A linear distortion compensation factor calculating part (18) estimates, based on quadrature demodulated signals (Ich, Qch), the linear distortion characteristic occurring mainly due to imperfection of analog circuits, such as a quadrature modulator (13) and a high-power amplifier (14), and calculates and outputs a linear distortion compensation factor for compensating the linear distortion. A linear distortion compensating part (12) performs a pre-distortion (addition of a reverse characteristic of the linear distortion characteristic) by multiplying the baseband signals (Ich, Qch) by the data of the linear distortion compensation factor.