A method for connecting equipment in a network system, enabling prevention of the spread of viruses throughout the network resulting from connection to the network of a server, client, PC, or other equipment infected with a virus, in which the network configuration is separated into an operation network and a virus check network using VLAN (Virtual Local Area Network) functions, and at the time of connection of equipment, a virus check is performed in the virus check network, and equipment confirmed by the virus check to be safe is accommodated in the operation network. When safety cannot be confirmed through the virus check, the equipment is isolated from the operation network and from the virus network.