PURPOSE: To shorten the time required for a bridge on the opposite side to learn position information of a station by generating a message which has the address of the transmission source station of a received message as the transmission source station and has an ineffective destination station address at the time of receiving this message in a network where a reception destination station receives the message and transmitting this generated message to a network other than the network where the message is received.

CONSTITUTION: After updating information of a station 2A in an internal memory, a bridge circuit 62 which receives the message transmits a message, which has the transmission source address as the transmission source address of the received message and has reception destination address '0' and has no information, to a network. By this operation, information of movement of the station 2A from a network A to a network C is quickly transmitted to bridge circuits in the whole of the network.