PURPOSE: To form a three-dimensionally formed article in one stage without subjecting the same to plural stages by providing a pair of forming dies which can be respectively independently driven freely attachably and detachably, and changing the position of the forming dies with respect to a member to be worked as desired according to the progression of working.

CONSTITUTION: A work piece W is placed on a blank rest 1a, and a blank holder 1b is brought near the rest 1a to grasp the work piece W. Forming dies 2 positioned on both sides of the work piece W are moved by a ram 3 to be brought closer to each other. The positions of the top and bottom forming dies 2b, 2a with respect to the work piece W are detected and the outputs thereof are fed to a position control device 4. The die 2a is advanced progressively from the state in which the projecting parts of the dies 2a, 2b are held in press contact with the work piece W grasped in the holding part 1 and the die 2b is retreated to form the work piece. When the dies 2 arrive at prescribed position, the positions thereof are detected, and the advancing and retreating of the dies 2 are temporarily stopped, whereafter the dies 2 are retreated to the home position and the holder 1b is detached from the rest 1a, then the work piece W is removed from the device.