Abstract: A network address managing system includes ports distributed over a network, and nodes constructed to be connected to the ports in a plug-in manner. Each of the ports includes a port identifier storage section for setting a unique port identifier. Each of the ports further includes a port control section for determining a coincidence between a port identifier ID, which is sent over the network along with a node address, and a port identifier ID stored in the port identifier storage section. Upon determination of such a coincidence, the port control section stores the node address transferred in the node address section. When a node is connected to the port, the control section trasnfers the stored address to the node. Each of the nodes includes a node address storage location for storing a node address, and a node control section for storing the node address transferred from the connected port in the node address storage section of the node.