A method of operating a base station and an apparatus for transmitting multicast data in a broadband wireless communication system are provided. The method includes receiving multicast data including a multicast Internet Protocol (IP) address from a source terminal, the multicast IP address being an address used in a network layer, and transmitting the multicast data to at least one terminal by including the multicast IP address to a control message of a Media Access Control (MAC) layer. The sending of the MAC layer control message including the multicast IP address includes, when a corresponding terminal is in an idle mode, sending a paging message including at least part of the multicast IP address, after sending the paging message, sending a resource allocation MAP message for multicast transmission including at least part of the multicast IP address, and transmitting the multicast data based on the resource allocation MAP message.