Operation of a network which comprises a plurality of mutually connected subordinate-networks is performed. Operation information is unitarily managed transmitted and received in the entirety of the network. An information storing unit stores operation management information used for the network operation management. A communications unit transmits and receives the operation information. Control is performed so that when the operation information is received from a subordinate-network, updating processing is performed if the contents of the operation information should be affected in the operation management information, and, operation information for reporting is produced and distributed to needing subordinate-networks based on the operation management information if reporting processing should be performed.