PURPOSE: To prevent the double punching of mutual punched comb teeth and the breakdown of a tool and product by making a blank hoop the partial punching of the half punching state in specified depth and the state of the other part being completely punched in the vicinity of the prepared hole at both sides.

CONSTITUTION: The prepared holes 13a, 13b of a blank hoop 10 are punched first. The hole 13a and 13b are alternately arranged respectively, one part is arranged at the pitch (b) of feeding amt. in the feeding direction and the other part is arranged by sliding the half pitch (c) of the feeding amt. Comb teeth 14a, 14b are then subjected to partial punching in the space with the punched holes 13a, 13b. The comb teeth 14a to be punched is completely punched from the comb teeth 14b to be left excepting the half punching parts 24, 26 of the length (i). The depth (j) of the half punching parts 24, 26 had better deeper for the parting at the post stage, but a rupture may arise, so it is made in the half punching state of more than the half of the plate thickness (k) of the blank hoop and less than the plate thickness (k). The blank 11 thereof is then fed to a parting stage by cutting it to part the half punching state.