In the present paper, we designed a specific router which provides the required level of QoS over NGN(Next Generation Network) by controlling data flows. We called this router QoS-Adaptive router, which consists of two parts, a legacy routing part and a QoS guarantee routing part. In order to provide differentiated services, QoS-Adaptive router enables data taking broad bandwidth or data requiring high-level QoS to be processed immediately and not to be affected by other services. And, we used the definition of flow for per-flow management, and assigned new service types to the flow label field of IPv6 header so as to provide differentiated services according to the packet type. By doing this, we designed a distinguishing mechanism in order to adapt to NGN that concentrates upon QoS. We built not only a small network to test QoS-Adaptive router but also a simulation environment called OMNeT++, and we could verify the performance of QoS-Adaptive router supporting QoS based on subscriber and service levels.