An audio mixing device that can get simpler processing done safely without depending on the property of an input signal is provided. An audio mixing device includes: an analyzer circuit to receive and separate audio data into primary and secondary audio data and control data; decoder circuits for decoding the primary and supplementary audio data separated into primary and supplementary audio signals in multiple channels; a mixer circuit for generating an M-channel composite audio signal by adding the supplementary audio signals to the primary ones channel-by-channel and converting the M-channel composite audio signal into N-channel audio signals (where N