Abstract: Although music program data has been recorded on a disc, imperfect index data or a signal has been recorded so that music program data is prohibited from being reproduced. To allow music program data to be reproduced, the index data is rewritten to perfect index data or a permission signal that allows music program data to be reproduced is transmitted through a communication line. Thus, music program data can be reproduced from the disc. Since music program data is not directly transmitted, the data transmission time is shortened. The music program data can be downloaded at high speed. In addition, the charging process can be smoothly performed. Moreover, music program data can be prevented from being illegally used.