PURPOSE: To provide a fading distortion compensating method capable of simultaneously compensating the deviation of a quadrature axis and fading distortion.

CONSTITUTION: In this fading distortion compensating method for inserting known signals in transmission data on a transmission side for performing quadrature amplitude modulation and compensating the fading distortion of reception signals based on the known signals on a reception side for performing quadrature amplitude demodulation, the known signals 1 to 4 are arranged at signal points provided with the maximum amplitude of plural quadrants on the transmission side and the fading distortion is compensated so as to let the known signals of the different quadrants be closest to the respective optimum points on the reception side. As the result of compensating the distortion of the plural signal points corresponding to the known signals so as to be minimum, the deviation from original positions at all the signal points is approximately uniformly suppressed to a small value.