The invention relates to a network management method wherein: a service management equipment holds the mapping of services and virtual networks as management information; a managed server sends an advice to a VLAN management equipment when its status changes; and the VLAN management equipment receives the advice and refers to the information contained in the advice to thereby identify the managed server and the connection port of a network switch, and configures a virtual network belonging to the identified port of the network switch. The method alleviates the task of reconfiguration associated with the adding or deleting of servers.