PURPOSE: To facilitate the positioning of a rotary shaft and a frame by inserting the rotary shaft integral with a cylinder block into a positioning jig having a hole of an inner diameter equal to the outer diameter of the shaft, and inserting a positioning jig of an outer diameter equal to a frame opening diameter into the opening.

CONSTITUTION: Placing a compression mechanism section 3 on a work table 11, part of a sub-bearing 9 is inserted in a hole 11a of the table 11. Under this condition, a rotary shaft 4 and a main bearing 8 are inserted from a bearing insertion hole 10b side of a positioning jig 10. Because the outer diameter of the rotary shaft 4 is approximately the same with the inner diameter of the rotary shaft insertion hole 10a, positions of the jig 10 and the rotary shaft 4 are determined and the positions of the jig 10 and the cylinder block 6 are also determined. When a frame 5 is inserted from the side of a tapered portion 10c of the jig 10, the positions of the frame 5 and the jig 10 are determined. Aligning the bolt holes of the frame 5 and the block 6, the frame 5 is secured to the block 6 by inserting a bolt 7.