1. A method for managing a network of an overlay network comprising: selecting a service according to a predetermined service QoS among network management services provided from a service provider in response to a request of a network manager; providing the selected service by performing to the network manager; and performing the service QoS and monitoring whether the provided service is matched with the serviced QoS or not, wherein the network management service is provided to the overlay network by being published by a low-level network of the service provider, wherein the network management service published from the low-level network is provided as a composition service or a basic service to the network manager according to the request of the network manager, wherein the request of the network manager according to an event of a managed element included in the network is provided to the overlay network, wherein a commands from the overlay network in response to the request of the network manager is provided to the network manager, and is published to the managed element, wherein the service QoS guarantees an end-to-end in the overlay network, wherein the service QoS is classified a service related QoS for a service performed in the overlay network and a transport related QoS, wherein the transport related QoS is a QoS related to the low-level network of a service provider or related to a network connected to the overlay network, wherein the service related QoS denotes requirements to constituent entities related to the service, and relates to service availability, accessibility, a response time, and a processing amount, and wherein the transport related QoS denotes requirements related to transport related constituent entities, and relates to a bandwidth, delay, and packet loss amount.