A disk device includes a top cover and a disk medium with a recording surface. The top cover includes a center horizontal portion having a surface which extends from a center point of the disk medium along the recording surface to an outer peripheral portion, a curved portion having a surface which extends from the outer peripheral portion of the center horizontal portion in a direction away from the recording surface, and an outer horizontal portion having a surface which extends from the curved portion in a direction away from the center point and along the recording surface. The recording surface includes a first zone in which data is set to be written, and a second zone in which data is set not to be written, the second zone being disposed adjacent to the first zone on an outer edge side of the disk medium from the first zone.