In a network management apparatus which manages a network composed of network elements installing different communication technologies such as an ATM, an MPLS, and a Diff-Serv, a QoS guarantee path route candidate retriever retrieves a route enabling a predetermined QoS to be guaranteed or a route enabling the predetermined QoS to be guaranteed by being assigned with the flow identifier from among routes between a source and a destination network elements based on network configuration information, QoS guarantee capability information, the flow identifier assignment capability information, and a QoS guarantee path establishing portion performs a QoS guarantee setting and a flow identifier assignment setting to the network elements on the retrieved route.