An audio decoding device comprises an audio decoding section for decoding first stream data and second stream data to generate two pieces of audio data and a data processing parameter, an external setting section in which a parameter corresponding to the data processing parameter is set, and an audio data processing section for processing the two pieces of audio data. When the data processing parameter contained in the second stream data is inappropriate, the audio data processing section performs data processing using the parameter set in the external setting section. When the data processing parameter contained in the second stream data is appropriate, the audio data processing section performs data processing using the data processing parameter generated by the audio decoding section.