A repeater for sending and receiving a routing message for changing routing information determines whether a routing message received from a first adjacent repeater which is disposed adjacent to the repeater is to be sent or not. If it is judged that the routing message is not to be sent, then the repeater generates a pseudo-routing message and sends the generated pseudo-routing message, instead of the routing message received from the first adjacent repeater, to a second adjacent repeater which is disposed adjacent to the repeater.