To reduce the setting work of an inter-network connection device by switching static routing control to dynamic routing control in accordance with an artificial instruction and dynamically updating the routing table.

When a repeating processing part 15 receives repeating data from a LAN interface processing part 16, it refers to the routing table 19b, decides a repeating destination router and transmits repeating data through an ISDN line. A route control management part 13 moves an inner operation from an operation state to a routing collection state based on the instruction of a manager and gives the instruction of routing information collection to a route control part 14. The route control part 14 transmits packets requesting routing information to the other routers by broadcasting and receives a response packet. The route control part 14 rewrites the routing table 19b with received routing information.