A network system comprising general management consoles 9, which are connected to the Internet 8; a supervisor management console 4, which can be accessed by a device management server 2; a database 5, which is connected to the device management server 2, wherein company data, correlated with each general management console 9, and device data, for each device 10 correlated with the company data, are stored; a console manager 3, for relaying the data processing; and means for referring to the company data and the device data to permit the correlated general management console to provide a correlated service or device or group. Since only a management console is installed in a company, the company is relieved of its responsibility for providing for the complicated operation of a management server. Furthermore, since the fee that an ISP may charge for providing a device management service for multiple companies can be split among the relevant companies, the expense incurred by each company can be reduced.