a plastic working method and apparatus which performs swiveling motion of an upper die mounted on a die holder . a toggle mechanism is provided for power assisting function . the toggle mechanism includes a link and the die holder . upper and lower end portion of the die holder are movably supported by upper and lower double eccentric rotary mechanisms for changing orientation of the die holder . the link is disposed within the die holder and has upper end supported by a machine frame and a lower end supported by the die holder . orientation of the link is also changeable .