A digital watermark embedding apparatus generates an echo signal, which is delayed a time period corresponding to digital watermark information to be embedded with respect to each tone signal that forms an original audio signal, and inserts the generated echo signal in the original audio signal by spreading the echo signal on the time axis, thus outputting a watermarked audio signal. A digital watermark detection apparatus despreads echo signals contained in the watermarked audio signal on the time axis, and extracts digital watermark information from the generation time of the despread echo signal contained in the watermarked audio signal.