PURPOSE: To enable the extrusion of an aluminum-made round bar having fiber structure and high strengthening at high extruding speed in the good productivity.

CONSTITUTION: A die 1 provided with an extruding material introduce inlet 3 at the rear end surface and also, a material guide passage 4 having a prescribed length extending in the front and rear direction communicated between the introduce inlet 3 and a die opening 2, is used. Then, the material guide passage 4 is formed into a profile regulating the difference between the max. value and the min. value of the strain velocity to within 50% of the max. value in the corresponding strain velocity histrical range of the extruding material B from the starting position of material deformation to the completing position of material deformation.