To provide a route information managing device which suitably manages route information.

A communication controller 10 includes a plurality of ports for connections with a plurality of networks; a database stored with an IP address of a communication device and a port to which communication data to be transmitted to the communication device should be output in a correspondence state; a retrieval circuit which retrieves the IP address of a communication device as the destination of the acquired communication data from the database; a processing executing circuit which sends out the communication data from the port made to correspond to the IP address of the communication device as the destination of the communication data; and a decision unit, sending the communication data transmitted to a route calculating device 856 which does not send it to the retrieval circuit, but to the route calculating device 856. The route calculation device 856 includes a calculation unit 857, which acquires route information transmitted from other routers from the decision unit and calculates a route table, based on the route information, and a database update unit 858, which reflects the route table calculated by the calculation unit 857 on the database.