In order to reduce the power consumed when using FFT processing and filtering in the frequency domain together, a digital filter device according to the present invention is provided with: a first filtering means for performing a first fast Fourier transformation using a first data sorting process, first filtering in the frequency domain, a first inverse fast Fourier transformation using a second data sorting process, and overlap removal on a first input block including overlapped data; a second filtering means for performing a second fast Fourier transformation, which simultaneously processes all data in a second input block including overlapped data, second filtering in the frequency domain, a second inverse fast Fourier transformation, which simultaneously processes all received filtered data, and overlap removal; and a data selection means for selecting either the first filtering means or the second filtering means, wherein the operation of the filtering means that is not selected by the data selection means is interrupted.