To provide a method for discriminating a fault of a distortion compensation nonlinear power amplifier capable of easily carrying out the discrimination on whether or not the power amplifier is in a fault state in a real operating state.

A distortion compensation table 2 receives a signal from a demodulation section 1, arithmetic operations of addition or multiplication of a distortion compensation value for compensating nonlinear distortion to or with the signal from the demodulation section 1 are carried out, a modulation section 3 receives an output of the table 2, a nonlinear power amplifier 4 amplifies an output of the modulation section 3, a distortion detection section 7 compares a signal negatively fed back from part of the amplified output with the signal from the demodulation section 1, calculates the distortion compensation value on the basis of a result of the comparison, and a fault discrimination means 11 discriminates a fault of the power amplifier on the basis of a result of the comparison. In the actual operation, a pseudo signal is given to the distortion compensation table 2 and the fault discrimination means 11 discriminates the occurrence of a fault by comparing the history of the distortion compensation table 2 before the pseudo signal is given to the distortion compensation table 2 with the history of the distortion compensation table 2 after the pseudo signal is given to the distortion compensation table 2.