When device information is transmitted from a DVD recorder to a server, the server transmits selectable function information that is selectable in the DVD recorder side to the DVD recorder. If a reproducing function for MP3, for example, is selected from the selectable function information, the DVD recorder transmits information of reproducing function for MP3 to the server. The server transmits amount billed for the reproducing function for MP3 and the like to the DVD recorder. A user makes the DVD recorder transmit a password when the user approves the amount billed. If the server judges that the password is correct, the server transmits a firmware related to the reproducing function for MP3 to the DVD recorder, then the DVD recorder rewrites an existing firmware that is stored in a flash memory to a firmware on which the firmware related to reproducing function for MP3 is added.