A turbine rotor blade according to the present invention includes a cover provided at the top of an effective blade portion and a blade-fitting portion provided at the bottom of the effective blade portion. A turbine wheel is provided with a turbine-wheel engagement portion to which the blade-fitting portion is fittable. The turbine rotor blade is a portion of a blade array structure formed by arranging the cover and a neighboring cover in contact with each other. The blade-fitting portion is provided with an anti-twist segment, and the turbine-wheel engagement portion is provided with an untwist restraining segment engageable to the anti-twist segment.