PURPOSE: To miniaturize a device and to reduce the cost of installment by providing a piston rod movably in a liquid pressure room and controlling the facing liquid pressure by this piston rod.

CONSTITUTION: A plate material 30 is laid on a die 12, then, a punch 4 and a blank holder 7 is dropped in a 21b direction and stopped once at a position where the liquid pressure room 11 is closed completely by the blank holder 7. Then, when a knockout rod 20 is lifted in a 21a direction and the liquid pressure in a liquid pressure room 17 reaches a specified value, the punch 4 begins to fall again and is lowered as far as it is regulated by a slide stopper. The plate material 30 is pushed by the liquid pressure to the front end of the punch 4 and deep-drawn as it adheres to the front end of the punch 4. When the deep-drawing is completed, the punch 4 and the blank holder 7 are lifted in a 21a direction to thrust out a deep-drawn plate material 30 to the outside. Since the liquid pressure in the liquid pressure room 17 is controlled by the knockout rod 20 in this way, the device can be miniaturized and simplified.