A network system is a kind of large and complex systems and the network administrators are required exhaustive work to maintain the quality and functions of the network system. To reduce the load of administrators, systematic and intelligent facilities for the network management tasks should be realized and provided for administrators. In this paper, we propose a knowledge-based support method of the network management tasks using the active information resource (AIR) which has knowledges and functions for its information resource. Furthermore, a novel network management support system based on this method, called AIR-NMS, is also proposed by using the agent-based computing technologies. In the AIR-NMS, a lot of AIRs are defined and utilized in order to monitor and collect the status information of the network automatically. The AIRs are collaborated each other and inspect the behavior of the network. The network administrator can obtain useful supports for management in responses of AIR-NMS. Moreover, a prototype system is implemented to demonstrate and evaluate the essential functions of the AIR-NMS.