A plastic working method and apparatus which performs swiveling motion of an upper die (44) mounted on a die holder (40). A toggle mechanism is provided for power assisting function. The toggle mechanism (50) includes a link (47) and the die holder. Upper and lower end portion of the die holder are movably supported by upper and lower double eccentric rotary mechanisms (11, 26) for changing orientation of the die holder. The link is disposed within the die holder and has upper end supported by a machine frame (1) and a lower end supported by the die holder. Orientation of the link is also changeable.
