PURPOSE: To execute such extrusion forming as a failure of a stock leakage, etc., is not generated by allowing an annular deposition chamber and a container billet hole to communicate with each other by plural port holes.

CONSTITUTION: A conical recessed part 10 of a size roughly corresponding to a container billet hole 1a is provided in the center part on the rear end face of a male die 4. On the conical face of this recessed part 10, a circular extruding stock inflow port 11 is provided at an equal interval in the peripheral direction. On the front end face of the periphery of a forming projecting part 7 of the male die 4, an extruding stock outflow port 12 is provided at an equal interval in the peripheral direction. The extruding stock outflow port 12 is formed a little longer in its peripheral direction in an annular deposition chamber 9. Each stock inflow port 11 and each stock outflow port 12 are allowed to communicate with each other by a straight port hole 13 pierced with a drill in a state inclined to the outside to the front in the extruding direction. In the course of extrusion, back pressure to the male die 4 is suppressed small. Therefore, it does not occur that the extruding stock intrudes from between the male die 4 and the female die 3, and between a container 1 and the male die 4.