A scale-out of a gateway server is realized according to a rapid increase in communication volume, without incurring system down. A high-quality communication is provided to priority users even during scaling out the gateway server. A high-quality communication is continuously provided to priority users without incurring the system down even if the scale-out/in of the gateway server is repeated. A bandwidth control apparatus transmits packets to plural virtual nodes equipped in a server device, reads the packets from any high priority queue and any low priority queue which are associated with the subject apparatus, and limits the packets to an upper limit bandwidth determined for each of the virtual nodes, and changes association of the high priority queues and the low priority queues with the virtual node bandwidth limiters according to an instruction from the control server for determining the scale-out/in of the virtual node.