A router device includes a lower-layer information acquisition section for acquiring connection information of whether or not connected with a base station in an external network from a lower layer, and a route judgment section for transferring the received packet to the base station in the case of being connected with the base station and judging a transfer destination by looking up a routing table in the case of not being connected with the base station, when receiving a packet destined for a terminal in an external network from a radio terminal device in a same local network. Because the received packet is transferred to the base station during connection with the base station, the packet can be transferred to the external via the router intended by the terminal. Furthermore, the load in the local network can be reduced.