In an impulse response processing device, a waveform dividing part divides a waveform of an original impulse response into a plurality of blocks on a time axis. A time adjusting part performs a time adjustment to reduce a time difference between successive ones of the blocks. A waveform synthesizing part generates a waveform of a new impulse response by adding the blocks on the time axis after the time adjustment by the time adjusting part. Further, a windowing part performs a windowing process to multiply each block by a window function having a window width corresponding to a width of the block, a function value of the window function decreasing from a center to both ends of the block. The waveform synthesizing part generates the new impulse response using the blocks after the windowing process by the windowing part.