PURPOSE: To perform burring reversely to the moving direction of a movable die with a simple structure.
CONSTITUTION: As an upper die 2 and a lower die 3 come close to each other, the projecting part 3a of the lower die is fit in the recessed part 2a of the upper die, and drawing is thereby performed on a work 4 to form a protruding part 5 on the work. The work 4 is arranged on the lower die by being so positioned as the center of the protruding part 5 of the work 4 is aligned with the center of the burring pin 10 of the lower die. Then, the upper die 7 is lowered to come close to the lower die 8. When the upper die 7 is further lowered, the periphery of the protruding part 5 starts deforming downward. In the meantime, as the upper die 7 is lowered, the burring pin 10 is abutted on the center of the recessed part 5a formed on the back side of the protruding part 5 of the work 4, pushing upward the center of the recessed part 5a of the work 4. When the upper die 7 is further lowered to come close to the lower side, the center of the recessed part 5a of the work 4 is broken through by the burring pin 10, by which burring is performed.