PURPOSE: To automatically generate network constitution data.

CONSTITUTION: An address input means 23 inputs the addresses of respective entities. An entity sorting means 24 sorts respective entities in each subnetwork based upon the addresses of respective entities. A constitutional data generating means 25 detects the connection constitution of respective subnetworks by tracing a data transfer route among respective entities and generates constitutional data expressing the connection constitution. A tree structure transforming means 26 transforms the constitutional data into tree structure. A constitutional data output means 27 outputs the constitutional data.