A pitch enhancement apparatus that obtains an output signal by performing, for each time segment, pitch enhancement processing on a signal derived from an input audio signal, the pitch enhancement apparatus comprising: a pitch enhancement unit that performs, as the pitch enhancement processing, for each time segment, processing to obtain, as an output signal at each time of the time segment, a signal including the signal at the time, a first signal for enhancement that is the signal at a time which is an earlier time than the time by the number of samples To corresponding to a pitch period of the time segment, and a second signal for enhancement that is the signal at a time which is an earlier time than the time by the number of samples T -α corresponding to a pitch period of an α-th time segment previous to the time segment, where α is a value greater than or equal to 1, wherein the pitch enhancement unit obtains, as an output signal at each time of the time segment, an output signal including a signal obtained by adding the signal at the time, a signal obtained by multiplying the first signal for enhancement by pitch gain σ 0 of the time segment and a predetermined coefficient B 0 which is a value less than 1, and a signal obtained by multiplying the second signal for enhancement by pitch gain σ -α of an α-th time segment previous to the time segment and a predetermined coefficient B -α which is a value less than 1, characterized in that the pitch enhancement unit obtains a signal obtained by dividing the signal obtained by the addition by 1 + B 0 2 σ 0 2 + B − α 2 σ − α 2 + 2 B 0 B − α σ 0 σ − α as an output signal. a pitch enhancement unit that performs, as the pitch enhancement processing, for each time segment, processing to obtain, as an output signal at each time of the time segment, a signal including the signal at the time, a first signal for enhancement that is the signal at a time which is an earlier time than the time by the number of samples To corresponding to a pitch period of the time segment, and a second signal for enhancement that is the signal at a time which is an earlier time than the time by the number of samples T -α corresponding to a pitch period of an α-th time segment previous to the time segment, where α is a value greater than or equal to 1, wherein the signal at the time, a first signal for enhancement that is the signal at a time which is an earlier time than the time by the number of samples To corresponding to a pitch period of the time segment, and a second signal for enhancement that is the signal at a time which is an earlier time than the time by the number of samples T -α corresponding to a pitch period of an α-th time segment previous to the time segment, where α is a value greater than or equal to 1, wherein the pitch enhancement unit obtains, as an output signal at each time of the time segment, an output signal including a signal obtained by adding the signal at the time, a signal obtained by multiplying the first signal for enhancement by pitch gain σ 0 of the time segment and a predetermined coefficient B 0 which is a value less than 1, and a signal obtained by multiplying the second signal for enhancement by pitch gain σ -α of an α-th time segment previous to the time segment and a predetermined coefficient B -α which is a value less than 1, the signal at the time, a signal obtained by multiplying the first signal for enhancement by pitch gain σ 0 of the time segment and a predetermined coefficient B 0 which is a value less than 1, and a signal obtained by multiplying the second signal for enhancement by pitch gain σ -α of an α-th time segment previous to the time segment and a predetermined coefficient B -α which is a value less than 1, characterized in that the pitch enhancement unit obtains a signal obtained by dividing the signal obtained by the addition by 1 + B 0 2 σ 0 2 + B − α 2 σ − α 2 + 2 B 0 B − α σ 0 σ − α