Provided are a network system and a network bandwidth control management method capable of preventing packets that need to preferentially flow from being discarded at a time of high load. A network system includes an external switch that is provided between a virtualization platform and an external network and configured to control a bandwidth amount of packets flowing into an open virtual switch, and an network control management device that is configured to modify a configuration of bandwidth control and priority control of the external switch in response to addition or deletion of a service of the virtualization platform based on information acquired from compute nodes, a network node, and a controller node.