An encoding device configured to encode an input audio signal to generate an output audio signal, the encoding device comprising: a downsampler configured to extract a low frequency signal from the input audio signal by downsampling the input audio signal, the low frequency signal being the low frequency components of the input audio signal; a low frequency encoding unit configured to encode the low frequency signal; a band pass division filter configured to perform a band pass division on the input audio signal to divide the input audio signal into multiple high frequency band components forming a high frequency signal; an envelope information generating unit configured to generate envelope information representing the high frequency band components of the high frequency signal received from the band pass division filter; a pseudo high frequency generating unit configured to generate a pseudo high frequency signal for each high frequency band component on the basis of the low frequency signal and the envelope information; a noise envelope information generating unit configured to generate noise envelope information which is formed from information representing a noise boundary position for dividing a noise signal included in the high frequency components of the input audio signal into a plurality of zones, and information representing a noise signal gain of each zone divided at the noise boundary position, wherein the noise envelope information is generated by extracting the difference between the high frequency signal and the pseudo high frequency signal for each high frequency band component; a sine wave information generating unit configured to generate sine wave information used for obtaining a sine wave signal included in the high frequency components of the input audio signal at a frequency represented by the sine wave information and which designates the emergence position identified from the sine wave information as the start position, wherein the noise envelope information generating unit generates final noise envelope information by subtracting the sine wave signal from the noise envelope information for each high frequency band component; and an encoding stream generating unit configured to multiplex the low frequency signal, the envelope information, the sine wave information, and the final noise envelope information into an encoding stream to generate the output audio signal. a downsampler configured to extract a low frequency signal from the input audio signal by downsampling the input audio signal, the low frequency signal being the low frequency components of the input audio signal; a low frequency encoding unit configured to encode the low frequency signal; a band pass division filter configured to perform a band pass division on the input audio signal to divide the input audio signal into multiple high frequency band components forming a high frequency signal; an envelope information generating unit configured to generate envelope information representing the high frequency band components of the high frequency signal received from the band pass division filter; a pseudo high frequency generating unit configured to generate a pseudo high frequency signal for each high frequency band component on the basis of the low frequency signal and the envelope information; a noise envelope information generating unit configured to generate noise envelope information which is formed from information representing a noise boundary position for dividing a noise signal included in the high frequency components of the input audio signal into a plurality of zones, and information representing a noise signal gain of each zone divided at the noise boundary position, wherein the noise envelope information is generated by extracting the difference between the high frequency signal and the pseudo high frequency signal for each high frequency band component; a sine wave information generating unit configured to generate sine wave information used for obtaining a sine wave signal included in the high frequency components of the input audio signal at a frequency represented by the sine wave information and which designates the emergence position identified from the sine wave information as the start position, wherein the noise envelope information generating unit generates final noise envelope information by subtracting the sine wave signal from the noise envelope information for each high frequency band component; and an encoding stream generating unit configured to multiplex the low frequency signal, the envelope information, the sine wave information, and the final noise envelope information into an encoding stream to generate the output audio signal.