A network system in which an electrical apparatus having a battery which performs charges and discharges to supply electric power to the electrical apparatus and a managing server are connected by the network and perform a diagnosis of the battery provided for the electrical apparatus. The electrical apparatus accesses a Web page provided by the managing server through the network and then transmits an information file about the battery to the managing server. The managing server reads the information file to analyze the information about the battery and then transmits the analytical results to the electrical apparatus.