PURPOSE: To prevent the generation of end clogging without the lowering of efficiency and generation of inside flaw by providing a hole of a specified condition on the side of rear end of a material to be rolled which is fed to a Mannesmann piercer.

CONSTITUTION: In the manufacture of seamless tube by Mannesmann process, the hole which satisfies the condition of formula (1) and formula (2) described hereunder is provided on the side of the rear end of the material to be rolled which is fed to the Mannesmann piercer. 0.1 ≤ (a)/D ≤ 0.5... formula (1), 30mm ≤(b) ≤ 150mm... formula (2). Where, (a): diameter of hole, (b): depth of hole, D: diameter of material to be rolled.