A rotor (10) of a rotary machine (T1) according to the invention includes a plurality of rotor members (20, 30, and 40) which are joined to each other in the axial direction in which the axis (P) extends, and among the plurality of rotor members (20, 30 and 40), the first rotor member (30) in hydraulic fluid injection portions (3a and 3b) of a passageway (3) is formed of Ni-based alloy so that the inside thereof is hollow throughout the entire length in the axial direction.