To make it possible to provide high-quality music signal regardless of the advertising voice superimposing position, an encrypted pure music signal input through a transmission medium and an unencrypted advertising voice signal are separated by a signal string separation section. A signal transform and combining section decodes the encrypted pure music signal and combines the decoded music signal with the advertising voice signal into a resultant signal of the music and advertising voice signals, then outputs the resultant signal to a code string combining section, which then combines the encrypted pure music signal and the resultant signal of the music and advertising voice signals and supplies the result to a recording section for recording the result on a magneto-optic disc.