A positioning plate of this invention comprises an outer side plate of a torus shape having an outer side plate hole formed eccentrically of the outer circumference, and an inner side plate of a torus shape having such an inner side plate hole eccentrically of the outer circumference that a leading end portion is fitted. The outer side plate is fitted in a stationary die hole, and the inner side plate is fitted in the outer side plate hole of the outer side plate.