PURPOSE: To form into three-dimensional shape quickly thus to insure high working efficiency, by pressing the end portion of a blade having preliminary shape through metal dies thereby deforming plastically while providing pressing process for forming a three-dimensional face on that blade.

CONSTITUTION: An impeller 14 has such shape as the innercircumferential edge section 26 of a blade 24 is simply projected upwardly to enable demolding. In order to fit the boss section 18 of said impeller 14, in a recessed section 20, it is placed on a block 16 and a positioning member 56 is projected to perform positioning. Then a press member 12 is driven toward a holding table 10 to contact a metal mold 54 at the tip of a rod 36 against the edge section 26 thus to bend it, and the edge section 26 is deformed plastically to form a three-dimensional face. Upon completion of bending work, the press member 12 is driven in the direction to be departed from the holding table 10, while the positioning member is separated from the impeller 14 to complete the working.