1. An information processing apparatus comprising: an identification unit for identifying the owner of each file and directory belonging to a virtual tree when restoring a backup of the virtual tree, the virtual tree being a virtual file system tree composed of, from among one or more files and directories forming a file system, only the files and directories accessible for a target user; and a restoration unit for comparing, when it is found, based on the result of the identification by the identification unit, that the owner of any of the files and directories is not the target user, the update time and/or version of the backup file or directory with that of the corresponding present file or directory, and when the update time and/or version of the backup file or directory is older than that of the corresponding present file or directory, restoring the backup file or directory back into a special directory accessible by the target user while maintaining the tree structure of the original virtual tree.