Predistortion effective for a power amplifier with the memory effect is provided. An A/D converter digitizes a signal voltage value after quadrature modulation, and the result is supplied to a subtractor. A lookup table outputs voltage value data in accordance with an output of the subtractor. The output of the lookup table is used as address data for accessing respective lookup tables. The lookup tables output an accumulation adding value derived from multiplying, by impulse responses, the signal voltage value after quadrature modulation and supplies it to the subtractor. The voltage value data outputted from the lookup table is converted by a D/A converter to output it as a predistortion signal for amplitude component for the power amplifier.