Patent ID: 8201162

Claim:
A software updating method for performing of software used in a user terminal device, the method comprising: determining at the user terminal, by referring to a version information server, whether a version of the software that is used in the user terminal device is a new version; storing information pertaining to operating systems of a plurality of user terminal devices; detecting an operating system of the user terminal device to be updated; sending from a file server to the user terminal a file to be used for updating to the new version according to the detected operating system of the user terminal device, the version of the software and list information indicating files necessary for execution of the software after the update to the user terminal device when the version is determined not to be the new version, the file server being determined based on a location of the user terminal device; and executing, in the user terminal device, update work and deletion of files unnecessary for execution of the software after the update, the files to be deleted being determined based on the list; wherein the file to be used for the updating is a compressed differential file specifying the differences between the software used in the user terminal and the new version, and the compressed differential file is expanded at the user terminal only after all unnecessary files are deleted from the user terminal.