PURPOSE: To enhance the accuracy of roundness of a stator frame engaging part after casting by partly burying a bearing bracket and a ring in both side ends of the frame of a lost foam pattern.

CONSTITUTION: A component of a bearing bracket 3 made of different metal is fixed to one end of a lost foam pattern 13, and a component of a ring 12 made of different metal is fixed to the other end. Then, the components of the bracket 3 and the ring 12 are cast in insert in the pattern 13 by transferring the molten metal of the pattern 13. Thus, since the bracket 3 and the ring 13 are partly buried in both side ends of a stator frame 1 of the pattern 13, the rigidity of the pattern 13 is increased. Thus, the deformation of the pattern 13 at the time of casing in insert can be prevented, and the accuracy of roundness of a stator 1 engaging part after casting can be enhanced.