The invention aims to converge predistortion coefficients efficiently in a predistorter adapted to compensate for distortion generated in an amplifier. Level detection means (11) detects the level of a signal input to an amplifier (4). Signal acquisition means (5-7) acquire a signal output from the amplifier as a feedback signal. Correspondence acquisition means (14) updates a predistortion coefficient expressed using a set of orthogonal polynomials so that a distortion component contained in the acquired feedback signal is reduced and acquires a correspondence between the level of the signal input to the amplifier and a control coefficient for predistortion (contents of a distortion compensation table (12)). Predistortion executing means (13) applies distortion for predistortion with respect to the signal input to the amplifier in accordance with the control coefficient for predistortion that corresponds to the detected level based on the acquired correspondence.
