PURPOSE: To make change and coupling of die parts safely and at high efficiency by providing a pressure receiving member and a locking member in an upper plate, and coupling the upper plate and die parts automatically by upper plate pressure welding of a slide.

CONSTITUTION: A lower plate 6 and a lower die 5 are fixed on a bolster 1, and an upper die 3 is combined and placed on the lower die 5. When the upper plate 4 is placed on the upper die 3 by slinging work under this condition, the locking member 12 faces the locking part 3A of the upper die 3 rightly. When the bolster 1 is set in the press machine and the upper plate 4 is pressure contacted by a slide 2 under this condition, a pressure receiving member 16 goes down and its cam member 16A pushes a cam roll 15 on rear end of the locking member 12, and front end of the locking member 12 is pushed out in the direction of the locking member 3A of the upper die 3 and pressure contacted to the locking part 3A of the upper die 3. Thus, the upper plate 4 unified with the upper die 3 is coupled to the slide 2 by a bolt 19 and a T nut 22.