The present invention relates to a method of rerouting a PVC route on an ATM network by previously defining an alternate route for the PVC route and by switching the PVC route to a previously defined alternate route when a fault occurs in a network element forming the PVC route. Further, the present invention relates to a network management system connected to a plurality of network elements, and includes an ATM network resource managing unit for managing resources included in the ATM network; a PVC connection managing unit connected to the element data collecting unit through the LAN or WAN for managing situation of connection of the PVC route; a PVC route searching unit for searching the PVC route; a fault event analyzing unit for receiving a fault from the fault notifying unit through the communication network when the fault occurs at any one of network elements, and analyzing the fault; an alternate route defining unit for previously defining the alternate route for the PVC; and an alternate route processing unit for switching a faulty route to the alternate route defined by the alternate route defining unit when the fault occurs at any one of network elements.