To enable reproduction of sound with high quality by reducing noises caused by embedding of watermark information when reproducing sound signal where watermark information is embedded as sound.

The sound signal in which a pseudo noise signal corresponding to each symbol constituting the electronic watermark information is analyzed, and the electronic watermark information is estimated. The pseudo noise signal corresponding to the symbol train estimated to be embedded is subtracted from the sound signal by spectrum subtraction, and then the sound signal is reproduced as sound.