According to prior art techniques, it is not possible to set virtual groups of network devices between SANs and IP networks and to provide virtual connection control of network devices between SANs and IP networks. A network system having an IP network for interconnecting network devices constituting SANs, is provided with a virtual group conversion device for converting, when information including an identifier for identifying a virtual group in the IP network is received, the received identifier into an identifier for identifying a virtual group in the SANs and transmitting the converted identifier to a SAN virtual group setting device, and for converting, when information including an identifier for identifying a virtual group in the SANs is received, the received identifier into an identifier for identifying a virtual group in the IP network and transmitting the converted identifier to an IP virtual group setting device.