To provide a method and a device for processing communication protocol which can improve the processing speed at a low cost.

This communication protocol processor is equipped with; a higher-layer processing part 1 which processes higher layers such as the application layer; a multiplexer demultiplexer 2; a transport layer processing part 3 which performs the processing of the transport layer; a network layer processing part 4 which performs the processing of the network layer; a multiplexer demultiplexer 5; a link layer processing part 6 performs the processing of the link layer; and a physical layer processing part 7 which performs the processing of the physical layer such as control over communication media 8. The processing of the network layer and the processing of the transport layer are performed in parallel, and hence the processing of a communication protocol can be made faster. The parts except the higher-layer processing part 1 which performs the processing of the application layer are all actualized by hardware, so the parallel processing making good use of the characteristics of the hardware becomes possible.