A method is designed for embedding an identification code into a musical apparatus which is allotted a serial number. The method is carried out by the steps of accepting an input of the serial number by a user of the musical apparatus, applying a specific operation to the accepted serial number to generate the identification code which is associated with the serial number and which is capable of uniquely identifying the music apparatus, and writing the generated identification code into a specified address of a nonvolatile memory which is integrated in the music apparatus such that the written identification code is never rewritten inappropriately.