PURPOSE: To improve the mechanical strength of a porous forming die produced by electroforming.

CONSTITUTION: A matrix having the same external shape as a formed article with the surfaces of the conductive part and insulating part made microporous is used in electroforming. Consequently, an overvoltage is produced at the boundary part between the conductive part and insulating part, many fine hydrogen bubbles are generated, Ni is extended to enclose the bubbles and deposited, and a for porous forming die main body 2 is obtained. The diameter of the pore 2a of the main body 2 is gradually increased toward the rear side. A backing 3 of metallic porous body is provided on the rear of the main body 2 to close the pore 2a, and a porous forming die 1 excellent in mechanical strength is obtained.