Abstract: Provide are a medium access control MAC device for processing data at a high speed and a method thereof. The MAC device includes a packet receiving and processing unit for receiving packet data transmitted from a physical layer device and extracting data and data information from the received packet data by processing the received packet data; a data multiprocessing unit for sequentially multiplexing the extracted data and storing the extracted data in a first memory; and a data arranging unit for arranging the stored data in sequence number order using addresses of the first memory and the extracted data information, and transmitting the arranged data to an upper layer interface.