PURPOSE: To firmly hold a stripper to a punching part owing to superior magnetic effect by disposing a magnetic holder at the end part of the stripper.

CONSTITUTION: When punching treatment is executed, a punching part 14 retreats upward. A plate P to be worked is inserted into the prescribed position between the lower part of the punching part 14 and the upper surface of a die 20. The punching part 14 moves downward to penetrate the plate P to be worked and advances into the opening of the die 20, whereas the stripper 24 is compressed between the plate P to be worked and a punch holding part 12 and is expanded outward. Next, when the punching part 14 retreats to the upper position again, the stripper 24 itself restores its initial shape. The stripper 24 will not be separated from the punching device 10 owing to the holding force of a magnetic holder 26 applied to the punch holding part 12. Thus, the stripper is firmly held to the punching part, and also the stripper is relatively manufactured at a low cost because of its simple structure.