This paper analyzes quantitative diversification by figuring production firm which creates music master-tapes. It is directed that the music creating business, which used to be vertical integrated into each record company, has been externalized to management and music publishing companies in previous studies. The development of Japanese music industry has reciprocally related to mass media, especially TV programs and commercial messages. Therefore, it is assumed that record companies have lost the rights of master-tapes. However, it is found that they have been possessed of the rights for music master-tapes since the 1980's including co-produced master-tapes. It is also indicated that record companies have supplanted management companies on the master-tape creation since around 1995. Thus, it is quantitatively proved that the actors for music creation are increased and varied from the production of master-tape perspectives.
