Disclosed is an audio watermark insertion method. The audio watermark insertion method includes performing a modulated complex lapped transform (MCLT) on a first audio signal, inserting a bit string of a watermark in the first audio signal obtained by performing the MCLT, performing an inverse modified discrete cosine transform (IMDCT) on the first audio signal in which the bit string is inserted, and obtaining a second audio signal, which is the first audio signal in which the watermark is inserted, by performing an overlap-add on a signal obtained by performing the IMDCT and a neighbor frame signal.