PURPOSE: To improve that efficiency and productivity by supplying partition fins from a through hole mounted on a mandrel, extruding a metallic pipe from a clearance between the mandrel and a die and inscribing the partition fins in the metallic pipe.

CONSTITUTION: The partition fins 13 are supplied from a through hole mounted on the mandrel 9 of a complicated die consisting of the mandrel 9 through which the through hole is mounted in the axial center and the die 10 arranged on its outer circumference. A metallic pipe 11 is extruded from a clearance between this mandrel 9 and the die 10 to manufacture a multiple-hole tube with these partition fins inside the metallic pipe 11. In this way, it is possible to effigiently manufacture the multip-hole tube excellent in pressure resistance and corrosion resistance and high in heat exchanger effectiveness by partitioning the inner part through the mid partition fins.