PURPOSE: To integrally extrusion-mold a hollow part and a solid part by sliding a core in the axial hole of a mandrel and freely opening and closing a communicating hole.

CONSTITUTION: When the core 2 of the mandrel 9 closes the communicating hole 13 of the axial hole 12, the material to be extruded flows in an annular clearance 11 between the mandrel 8 and a female die extruding hole 6 from a deposition room 7 in the centripetal direction to extrusion-mold a hollow material H. At this time, when the core 4 is moved backward by a driving device 5, part of a material to be extruded flowing through a port hole 10 flows from the communicating hole 13 into the axis 12. This material is extruded forward together with the material to be extruded passing the metal flow clearance from the opening at the tip of the mandrel 8 and the material is pressed at the position of a bearing 6a at the extruding hole 6 to extrusion-mold a solid material ES.