Patent attributes
At a reel, an outer peripheral surface of a cylindrical tube portion of a reel hub is a tape winding surface around which a magnetic tape is wound. In a free state, the tape winding surface forms a substantial taper shape in which an outer diameter is greater at an upper end portion side where a radial direction rigidity is relatively low, than at a lower end portion side where the rigidity is high. In a state in which a magnetic tape is wound, the tape winding surface can form a shape that is substantially symmetrical with respect to a transverse direction of the magnetic tape. As a result, the reel and a recording tape cartridge are obtained in which the outer peripheral surface of the hub forms a proper shape in a state in which a recording tape is wound.