PURPOSE: To prevent the damage to die during extrusion without reducing extrusion speed for also the extrusion of thin perforated tube or the like by specifically setting an approach angle from the basic part of projecting part for forming toward unit projecting parts for forming.

CONSTITUTION: A perforated tube 7 is manufactured by combining a male die 1 with the projecting part 2 which the plural unit projecting parts 3 for forming are arranged in line in the tip part with a female die 4 with an opening part 5 for forming which the row of the unit projecting parts is arranged at intervals of prescribed forming space 6. At this time, in the male die 1, the approach angle θ of the projecting part 2 for forming toward the projecting parts 3 from the basic part 11 is set within the range of 35 - 75°. Using these dies, the damage to die during extrusion can be prevented without reducing the extrusion speed so much. Accordingly, the productivity is improved.