A speech/audio coding apparatus, comprising: a receiver that receives a time-domain speech input signal; and a processor that transforms the time-domain speech input signal into a frequency-domain spectrum; divides a frequency region of the spectrum in an extended band into a plurality of divided bands; sets a limited band for a divided band of the extended band in a current frame, when a difference between a first frequency with a first maximum amplitude in a spectrum of the divided band in a preceding frame and a second frequency with a second maximum amplitude in a spectrum of the divided band in the current frame is below a threshold, wherein the threshold is equal to half-width of the limited band; and encodes the spectrum in the limited band within the divided band in the current frame, and does not encode a spectrum outside the limited band within the divided band in the current frame, wherein the processor sets the limited band such that the limited band includes both the first frequency with the first maximum amplitude in the spectrum in the preceding frame and the second frequency with the second maximum amplitude in the spectrum of the divided band in the current frame, and when a start frequency position of the limited band set for the divided band is lower than the start frequency position of the divided band, a start spectrum position of the limited band is set to the start frequency position of the divided band, and when an end frequency position of the limited band set for the divided band is higher than the end frequency position of the divided band, an end spectrum position of the limited band is set to the end frequency position of the divided band. a receiver that receives a time-domain speech input signal; and a processor that transforms the time-domain speech input signal into a frequency-domain spectrum; divides a frequency region of the spectrum in an extended band into a plurality of divided bands; sets a limited band for a divided band of the extended band in a current frame, when a difference between a first frequency with a first maximum amplitude in a spectrum of the divided band in a preceding frame and a second frequency with a second maximum amplitude in a spectrum of the divided band in the current frame is below a threshold, wherein the threshold is equal to half-width of the limited band; and encodes the spectrum in the limited band within the divided band in the current frame, and does not encode a spectrum outside the limited band within the divided band in the current frame, wherein the processor sets the limited band such that the limited band includes both the first frequency with the first maximum amplitude in the spectrum in the preceding frame and the second frequency with the second maximum amplitude in the spectrum of the divided band in the current frame, and when a start frequency position of the limited band set for the divided band is lower than the start frequency position of the divided band, a start spectrum position of the limited band is set to the start frequency position of the divided band, and when an end frequency position of the limited band set for the divided band is higher than the end frequency position of the divided band, an end spectrum position of the limited band is set to the end frequency position of the divided band.