Abstract: The present invention provides a router device capable of performing routing processing on each received packet at high speed by an IP routing accelerator without the interchange of transmission order of each packet in the same session. The router device registers a packet transmission destination and a session type obtained by analyzing each received packet in a transmission route information table in association with each other and at the same time transmits all received packets accumulated in a session-by-session transmission queue corresponding to the session type of the received packet.