In a turbine rotor blade assembly 1, a length h2 in the radial direction of a bucket dovetail 15 of a notch blade 10 is configured to be shorter than a length h3 in the radial direction of an effective blade portion 13 of a adjacent notch blade 30 and a length h4 in the radial direction of the bucket dovetail 15. Thus, during an insertion of the notch blade 10 in the axial direction, the rotational movement Rf around the radial direction and the circumferential movement of the notch blade 10 can be secured.