PURPOSE: To equalize the flow speed of a material to be extruded and to prevent generation of defects such as under fill of material to be formed by locating the surface of low coefficient of dynamic friction on the part where the flow speed of the material to be extruded is relatively lowered when the whole of bearing surface is composed of the surfaces where coefficients of dynamic friction are equal.

CONSTITUTION: When the whole of both male and female bearing surfaces 8, 12 is composed of surfaces where coefficients of dynamic friction are equal, a hybrid type die 1 for extrusion is composed by locating the surface where coefficient of friction is relatively lower on the part where the flow speed of the material to be extruded is relatively lowered. When the material 3 to be formed is extruded by use of that die 1, the speed of the material to be extruded, which is brought into flow along the inner surface and the continuing upper surface of a groove 13 with the section of downward C-shape on the bearing surface 12 of the male die, is increased and the flow speed of the material to be extruded along the bearing surface 12 is equalized. And, the deficiency and shortage of thickness of screwed cylindric part 2 of the material 3 are obviated.