Disclosed is a method for generating a Short Term Key Message (STKM) for protection of a broadcast service being broadcasted to a terminal in a mobile broadcast system. The method includes transmitting, by a Broadcast Service Subscription Management (BSM) for managing subscription information, at least one key information for authentication of the broadcast service to a Broadcast Service Distribution/Adaptation (BSD/A) for transmitting the broadcast service, generating, by the BSD/A, a Traffic Encryption Key (TEK) for deciphering of the broadcast service in the terminal and inserting the TEK into a partially created STKM, and performing, by the BSD/A, Message Authentication Code (MAC) processing on the TEK-inserted STKM using the at least one key information, thereby generating a completed STKM.