A frequency digital signal demultiplexing apparatus including: demultiplexing filter bank units connected in a multistage manner to form a demultiplexing filter bank, wherein each unit includes at least one filter for filtering an input signal in series with a down-sampler, and frequency conversion and decimator part to receive at least one of the received signal and output signals of each unit demultiplexing filter bank, which includes a frequency conversion part, for each input signal, to shift a frequency of an input signal, and at least one decimator part serially connected to an output of each frequency conversion part, the decimator part including a filter for performing band limitation of an input signal and a down-sampler for down-sampling an output signal of the filter and output a down-sampled signal.