PURPOSE: To prevent overlapping between self-address and other device address by storing self-address in a communication network, confirming the response state of other device by the operator, revising its own address and notifying its own address subjected to revision again.

CONSTITUTION: When an address noticing means informs its own address to other device, other device with the same address as its own address assigned already thereto outputs a response signal. Upon the receipt of the response signal by the reception means, a response informing means informs it to the operator. When the operator operates an operation means to instruct the revision of its own address, a clanging means revises its own address and an address storage means stores the address after the revision. Then the address informing means informs the address after the revision to other device again. Thus, the operator recognizes its own address.