Disclosed is an inter-entity coupling method for service protection in a broadcast environment including a terminal and a broadcast network, which includes a Broadcast Service Application (BSA), a Broadcast Service Distribution (BSD) and a Broadcast Service Management (BSM) function. The method includes executing enrollment and service joining procedures for the terminal, wherein the terminal acquires a group key in the enrollment procedure and acquires a Rights Object (RO) for the service in the service joining procedure; receiving a message including a traffic key in the terminal; acquiring the traffic key from the message using the RO; receiving an encrypted service encrypted by the BSD in the terminal; and decrypting the encrypted service using the traffic key in the terminal.