1. A distortion compensating apparatus comprising: a processing circuit that calculates each of a plurality of series operation coefficient pairs based on a transmission signal and a feedback signal of an output from an amplifying circuit performing power amplification of the transmission signal, executes a series operation process with respect to the transmission signal based on the plurality of the series operation coefficient pairs as a distortion compensation of the transmission signal, and inputs a result of the series operation process to the amplifying circuit performing the power amplification; and a selecting unit that, on the basis of power of the transmission signal, selects the series operation process to be executed corresponding to one of the plurality of series operation coefficient pairs, and selects one of the plurality of series operation coefficient pairs to be used in the series operation process to be executed.