To inexpensively cut fixing grooves by a simple means, and prevent generation of large stress in a part to which blades are fixed by forming the fixing grooves to install the blades on a rotor of a fluid machine along a helix on a peripheral surface of the rotor on which the blades are installed.

A rotor 1 of a gas turbine compressor has hubs 2a and 2b, and a large number of blade rows 3 are installed on a peripheral surface of the rotor 1. Rows of filling pieces 6 exist between the respective blade rows 3, and these filling pieces 6 regulate an interval between the blade rows 3, and join blades 5 in the shaft direction. The rotor 1 is divided into two areas, and the blade rows 3 having different pitches are arranged in the respective areas. Fixing grooves 7 in which the blades 5 or the filling pieces 6 are installed, extend in a helical shape 8 in the shaft direction on a peripheral surface of the rotor 1, and notch parts 9a and 9b are arranged in end parts of the fixing grooves 7 to which the blade rows 3 are joined, and these notch parts 9a and 9b are useful as a recess area of a molding milling cutter in the case of cutting work of the fixing grooves 7.