A carrier leak compensating device (2) for adding compensation values to a received transmission signal, an analog quadrature modulator (4), a feedback device (5-7) for receiving and quadrature-detecting part of an output signal of the analog quadrature modulator and outputting a feedback signal in which the frequency of each carrier signal is the same as in the transmission signal, a carrier leak detecting device (800) for detecting an I-phase carrier leak and a Q-phase carrier leak on the basis of the difference between cumulative addition values of an amplitude/phase-adjusted feedback signal and the transmission signal, and a carrier leak compensation value controller (9) for updating the compensation values on the basis of the detected carrier leak. The number of samples for the amplitude/phase detection may be smaller than the number of cumulative addition samples.