PURPOSE: To reduce the force applied to a wall part of a work and to obtain uniform side wall plate thickness by executing the ironing, while allowing a die having an ununiform surface to rotate against the work.

CONSTITUTION: A first stage of a die 1 is the upper tapered part 2 in which the inside diameter has become gently smaller from an inlet side of a work. A second stage is a bearing part 3 having the inside diameter being parallel to the center axis of the tapered part 2, and a third stage is the lower tapered part 4 in which the inside diameter has become larger toward an outlet from the bearing part 3 and which is opened in the lower end. Subsequently, plural tapered band-like undulated parts 5 are provided on a part extending from the inlet side of the tapered part 2 to the bearing part 3. In such a state, when a container has reached the inlet of the die, it comes into contact with the undulated part 5, and ironing is executed by the band-like undulated parts 5. In such a case, the ironing force in the peripheral direction decreases as an inclination angle θ increases.