Each wheel-side tab section of a turbine wheel is formed such that a bottom surface of a second groove are continuous with bottom surfaces of first grooves that are adjacent thereto. The outline shape of each wheel-side tab section when seen in an axial direction is a shape in which a portion of a particular shape is replaced with straight portions along predetermined straight lines. The particular shape includes a predetermined range of an outline shape of an attachment section as seen in the axial direction. The portion is at least on the radially inward side of the bottom surface of the second groove and is on an outer side, in the circumferential direction, of the predetermined straight lines. The predetermined straight lines pass through a central axis and points within a range along the particular shape from intersections with the bottom surface of the second groove to peaks of wheel-side hook portions adjacent, on the radially inward side, to the bottom surface of the second groove.