The present invention addresses the problem of increasing the likelihood of making it possible to reduce the consumption of power necessary for filter processing and the amount of heat generated during filter processing. In order to overcome this problem, a second complex signal and a third complex signal are generated from a first complex signal in a frequency domain, the third complex signal being a complex conjugate of the second complex signal. Signal selection is performed from the plurality of types of complex signals having different amounts of change in signal amplitude. Processing is performed on the complex signal selected as the signal using a first filter coefficient and a second filter coefficient. The complex signals after filter processing are synthesized to generate a complex signal, which is then outputted.