To provide a steam turbine rotor having an effective and simple anticorrosion structure against corrosive liquid created from steam in a gap part between a leg part of a moving blade and a fitting groove.

In this invented steam turbine rotor 1 having an axial entry type moving blade attachment part, a blocking plate 41 is used as a member surely retaining a moving blade 5 attached on a disk 3 on a rotor main body 2 in a longitudinal direction of the rotor main body 2 as compared with a conventional embodiment. The blocking plate 41 is a fan-shaped flat plate and has arc length capable of retaining a leg part 6 with extending over adjoining two moving blades 5, and has width W almost covering a caulking piece 61 and the leg part 6. The blocking plate 41 is inserted in blocking plate grooves 31, 31 formed on an end surface part of a section where the fitting groove for the disk 3 is formed, and arranged with abutting on side end surfaces 6a, 6a of the leg part 6 respectively, firmly retains the moving blade 5 on the rotor main body 2 in the longitudinal direction of the rotor main body 2, and blocks all gaps formed between the fitting groove 4 and the leg part 6.