PURPOSE: To manufacture a semi-open type radial impeller simply in a short time by pressing a disk and performing blanking and bending of blade parts at a time and attaching a boss to this.

CONSTITUTION: A disk 1 is pressed and blanking and bending of blade parts 3 are performed simultaneously. An impeller is manufactured by attaching a boss 2 to the pressed disk 1. In some cases, a backing plate 4 is attached to the back of the impeller to prevent flowing out of fluid from the parts blanked by the press. In some cases, balancing is effected by forming a hole 5 by making the diameter of the backing plate 4 slightly smaller than the maximum pitch diameter of the blades 3 and passing a thin plate 6 for balancing through the hole 5 and winding it around the impeller.