An extraction unit extracts, in accordance with a format of a file which the client apparatus requests a file storage apparatus to store to storing means, data possibly made into independent data as an independent file from the file which is data in a portion that can be stored to the storing means. A duplicate determination unit determines whether the storing means stores data matching the data possibly made into independent data that is extracted by the extraction unit or remaining data which are data obtained by deleting the data possibly made into independent data from the file. A storing processing unit stores, to the storing means, the data possibly made into independent data or the remaining data which do not match data stored to the storing means, on the basis of the determination result made by the duplicate determination unit. A restoring unit restores a file by connecting the remaining data and the data possibly made into independent data which are stored to the storing means by the storing processing unit, in accordance with a request made by the client apparatus.