Method and Apparatus for transmitting a MAC control message in wireless access system

Embodiment of the present invention provide a medium access control (MAC) method of transmitting control messages and an apparatus to support it for the M2M device. A method of transmitting a MAC control message according to an exemplary embodiment of the present invention is a broadcast assignment that represents the function index field, and a MAC control resource area in which a message is sent indicating that the information element (IE) carrying a broadcast allocation information for the M2M device information broadcast assignment that includes map information element indicates that for a cyclic redundancy check (CRC) bits are allocated M2M broadcast masking steps and broadcast assignment map information element for receiving (BA a-mAP IE), broadcast assignment information directed It may comprise the step of receiving a MAC control message via a resource region. In this case, CRC bits to be masked in the BA A-MAP IE is comprised of a masking prefix, a masking code for a 3-bit type indicator, and 12 bits of one bit, the masking code is masked in BA A-MAP IE for a M2M broadcast assignment that the decimal value is preferably used.