To prevent the thickness surface of a vane from being deposited thereover with a wear-resistant material.

A trapezoidal groove 51 having its width decreasing toward an opening, is longitudinally formed in a vane holding device 50. Further, A protrusion 26 having an inverted trapezoidal shape, adapted to be fitted in the groove 51 is formed on the rear part of a vane along the vertical direction. Further, the protrusion 26 of the vane 21 is inserted in the groove 51 of the vane holding device 50, and is slid therealong. With the repetitions of this steps, a plurality of the vanes 20 are set in the device 50 while the thickness surfaces of the vanes 20 adjacent to one another may be made into close contact with one another. With this arrangement, it is possible to prevent the thickness surfaces of the vanes from being vapor-deposited with a wear-resistant material.