To enable use of content data recorded in an arbitrary player using a mobile terminal, such as a cellular phone, in response to an inquiry made by a mobile terminal to a player, the player transmits a response to the mobile terminal. When a user performs a predetermined operation on the mobile terminal, the mobile terminal creates a one-time password and transmits the one-time password and operation information concerning the user-performed operation to the player. The player transmits a terminal ID and the like to a service center. Upon reception of the information, the service center creates a one-time password and transmits the one-time password and an operation permission command to the player. The player compares the transmitted password with the password created by the mobile terminal. When the passwords are verified, the user operation instruction is made valid.