Mechanisms for writing a file on a tape medium in a manner that enables high-speed reading are provided. A predetermined format is applied to the medium that divides the medium into a first region of a predetermined length in a longitudinal direction from a region of the medium, and a second region that extends from an end of the first region to a terminal region of the medium in a longitudinal direction and that has a predetermined width with respect to a width of the medium in a transverse direction. Writing a top data portion of a predetermined data amount of the data of the file in the first region and writing data of the file in the second region are performed.