An apparatus and method for circuit mode resource allocation in a Broadband Wireless Access (BWA) system is disclosed. The method includes generating a first resource allocation message which comprises currently used slot bitmap information with respect to a circuit mode region in a frame; allocating resources to one or more terminals with respect to currently unused slots in the circuit mode region according to the currently used slot bitmap information; and generating a second resource allocation message which comprises information relating to the resource allocation. Thus, the effective circuit mode resource allocation can be achieved without holes in the circuit mode, while maintaining backward compatibility with the existing standards.