A method of processing an audio signal, according to an embodiment of the present invention for solving the technical problem, further includes: receiving a signal for one channel pair element (CPE) to which internal channel gains (ICGs) have been pre-applied; when a reproduction channel configuration is not stereo, acquiring inverse ICGs for the one CPE based on Motion Picture Experts Group surround 212 (MPS212) parameters and on rendering parameters corresponding to MPS212 output channels defined in a format converter; and generating output signals based on the received signal for the one CPE and the acquired inverse ICGs.