The purpose of the present invention is to reduce leakage of an output signal between band-pass filters and in the time axis direction. A signal input part 1 vectorizes an input signal x(n). An extended impulse response matrix generation part 2 generates an extended impulse response matrix He in which impulse response vectors using impulse response sequences of band-pass filters as elements are extended in the time axis direction. An expansion coefficient calculation part 3 calculates an expansion coefficient vector {circumflex over ( )}y(n) using an input signal vectors  x(n) and the extended impulse response matrix He. A signal output part 4 outputs at least one of expansion coefficients corresponding to a center vector of the extended impulse response matrix He of the expansion coefficient vector {circumflex over ( )}y(n).