Abstract: An audio signal waveform emphasis processing device performs even-order integration on an input audio signal using one or a plurality of double integrators and even-order differentiation on the input audio signal using one or a plurality of double differentiators so as to obtain even-order integrated signal and even-order differentiated signal, and adds the even-order integrated signal and the even-order differentiated signal to the input audio signal in the same phase or reverse-phase with the input audio signal, whereby sound quality of audio signal in audio equipment is greatly improved by obtaining a desired frequency-gain characteristic without destroying the mutual phase relationship between, in particular, the middle frequency range vs. high frequency range and the middle frequency range vs. low frequency range frequency components close to the middle frequency range of an input audio signal.