PURPOSE: To extrude a material to be extruded by a low extruding force not applied so far, and to perform this extrusion by using a single-acting press system extrusion machine.

CONSTITUTION: A die 1 whose core 9 of a male die 7, is equipped with a mandrel passing hole 5, and a mandrel 3 insertable in a state fitted to the mandrel passing hole 5 of the die 1, are used. By driving a stem 11 forward at a state in which the mandrel 3 is inserted into a billet B in a container 10, the mandrel 3 is allowed to push forward by the stem 11 the billet metal B is inserted into the forming gap 6 of the die 1 while inserting the mandrel 3 into the mandrel passing hole 5 of the core 9 of the die 1.