In order to make it possible to reduce the storage capacity required for noise removal processing in, for example, multi-resolution analysis and the like, without affecting signal quality, the present invention is equipped with: a storage device into which a input signal of a first channel is written, the input signal branching off into at least first and second channels; a first frequency transform processing unit which transforms the input signal read out and inputted from the storage device into a frequency-domain to output a first signal; a second frequency transform processing unit which transforms the input signal inputted from the second system into a frequency-domain to output a second signal; a third frequency transform processing unit which transforms the second input signal inputted from the second frequency transform processing unit into a frequency range to output a third and fourth signals in the first and second frequency bands; a first inverse frequency transform processing unit; and a second inverse frequency transform processing unit to which directly or indirectly inputting the third signal from the third frequency transform processing unit is directly or indirectly inputted and the fourth signal from the third frequency transform processing unit is inputted, and which outputs a third transformed signal produced through performing inverse frequency transform on the inputted signals. Therein, the first inverse frequency transform processing unit, to which the first signal from the first frequency transform processing unit is directly or indirectly inputted and the third converted signal from the second inverse frequency transform processing unit is directly or indirectly inputted, outputs a signal produced through performing inverse frequency transform on the inputted signals.