An audio coding apparatus that codes an input multi-channel audio signal, said apparatus comprising: a downmix signal generating unit configured to generate a first downmix signal by downmixing the input multi-channel audio signal in a time domain, the first downmix signal being one of a 1-channel audio signal and a 2-channel audio signal; a downmix signal coding unit configured to code the first downmix signal generated by said downmix signal generating unit; a first t-f converting unit configured to convert the input multi-channel audio signal into a multi-channel audio signal in a frequency domain; a spatial information calculating unit configured to generate spatial information by analyzing the multi-channel audio signal in the frequency domain, the multi-channel audio signal being obtained by said first t-f converting unit, and the spatial information being information for generating a multi-channel audio signal from a downmix signal; characterized in that the audio coding apparatus further comprises a second t-f converting unit configured to convert the first downmix signal generated by said downmix signal generating unit into a first downmix signal in the frequency domain; a downmixing unit configured to downmix the multi-channel audio signal in the frequency domain to generate a second downmix signal in the frequency domain, the multi-channel audio signal being obtained by said first t-f converting unit; and a downmix compensation circuit that calculates downmix compensation information by comparing (i) the first downmix signal obtained by said second t-f converting unit and (ii) the second downmix signal generated by said downmixing unit, the downmix compensation information being information for adjusting the first downmix signal, and the first downmix signal and the second downmix signal being in the frequency domain. a downmix signal generating unit configured to generate a first downmix signal by downmixing the input multi-channel audio signal in a time domain, the first downmix signal being one of a 1-channel audio signal and a 2-channel audio signal; a downmix signal coding unit configured to code the first downmix signal generated by said downmix signal generating unit; a first t-f converting unit configured to convert the input multi-channel audio signal into a multi-channel audio signal in a frequency domain; a spatial information calculating unit configured to generate spatial information by analyzing the multi-channel audio signal in the frequency domain, the multi-channel audio signal being obtained by said first t-f converting unit, and the spatial information being information for generating a multi-channel audio signal from a downmix signal; characterized in that the audio coding apparatus further comprises a second t-f converting unit configured to convert the first downmix signal generated by said downmix signal generating unit into a first downmix signal in the frequency domain; a downmixing unit configured to downmix the multi-channel audio signal in the frequency domain to generate a second downmix signal in the frequency domain, the multi-channel audio signal being obtained by said first t-f converting unit; and a downmix compensation circuit that calculates downmix compensation information by comparing (i) the first downmix signal obtained by said second t-f converting unit and (ii) the second downmix signal generated by said downmixing unit, the downmix compensation information being information for adjusting the first downmix signal, and the first downmix signal and the second downmix signal being in the frequency domain.