To enable the drastical shortening of a molten metal impregnating time into a preform by forming the film layer of a metallic shielding material on the peripheral surface of the preform except the connecting part for a molten metal pouring cylinder, rotating this preform and impregnation-forming metallic matrix into the preform.

The preform 16 corresponding to a rotor shape is produced by using a ceramic material and the metallic shielding material 30 is coated on the outer peripheral part of the preform 16 except the erecting position of the molten metal pouring cylinder 26 to form the coating layer, and simultaneously, a peeling layer 28 is coated on a position corresponding to rotary center part of the inner surface in a hat part. Successively, the molten metal pouring cylinder 26 is erected in the inner surface of hat pattern of the preform 16, and the preform 16 is raised to the temp. in a furnace to burn off the binder in the preform 16. Thereafter, at the step of shifting from a preheating furnace to a impregnating furnace, while filling molten aluminum alloy to the molten metal pouring cylinder 26 connected with the preform 16, a rotary table 22 is driven to rotation. The formed product discharged from the impregnating furnace is supplied to a cooling device.