At an upload time, each of multiple printers connecting with a network identifies storage or non-storage of any unsent monitor information file, which has not yet been sent to a management server. In the case of storage of any unsent monitor information file, the printer collects from the other printers unsent monitor information files, which are stored in the other printers and have not yet been sent to the management server, and uploads the collected monitor information files and the unsent monitor information file stored in the self printer to the management server. This arrangement effectively reduces the access frequency from the respective printers to the management server for transmission of monitor information files from the printers to the management server.