A rotary unit includes a first taper tubular portion which is contiguous to a first axial direction side of a unit main body portion and in which a first unit end that is a first-axial-direction-side end of the rotary unit is positioned, an outer diameter of the first taper tubular portion becoming smaller toward the first axial direction. The rotary unit includes a first projecting portion extended on an outer peripheral portion of the first taper tubular portion with projecting toward an outer peripheral direction and wound toward a first around-axis direction that is one of directions around the longitudinal axis as the first projecting portion extends from the first axial direction toward a second axial direction.
