PURPOSE: To obviate direct action of the reaction by press working on a frame in the stage of turning opposedly disposed yokes in diametrically opposite directions and subjecting a material to press working by providing tie rods between the turning centers of the yokes.

CONSTITUTION: An eccentrical shaft 2 is rotationally driven around the axial center O by a driving device 1 to move connecting rods 4a, 4b in diametrically opposite right and left directions, thereby moving back and forth the rods. The yokes 8a, 8b are thereby turned around pins 7a, 7b, by which sliders 11a, 11b are moved so as to attach and detach in the right and left directions. The material 24 is press-worked by tools 23a, 23b. The reaction during the press working acts as tensile force on a tie rod 16 via the slides 11a, 11b, the yokes 8a, 8b, supporting blocks 6a, 6b, cylinders 18a, 18b, piston nut 17a, 17b and acts at the same time as compressive force on the rods 4a, 4b. Exertion of excessive moment on the frame 3 is thus obviated and the reduction in the size of the frame 3 is made possible.