A file system that is organized in an operating system to manage a file to be recorded in a recording device in compliance with a file access request from an application. The file system includes a first recording section recording in a recording device a file that includes a management information section and a data section. A second recording section, which, when the first recording section records the file that includes the management information section and the data section, adds, as needed, an extended management information section that records information other than the management information section about the data section.