To provide a manufacturing method of a seamless steel tube which is excellent in quality of internal surface.

This method is a method for manufacturing the seamless tube by piercing a billet by using a plug on the surface of which a scale film is formed. In the structure of the scale film, the plug on which the generation of the outer layer scale primarily composed of the layer of Fe2O3, Fe3O4 which is formed on the outward of the surface of the base metal of the plug is prevented or a plug from which the outer layer scale primarily composed of the layer of Fe2O3, Fe3O4 is removed is used. Consequently, dropout of the outer layer primarily composed of Fe2O3, Fe3O4 on the way of piercing disappears and the defect on the inside surface and Mannesmann rupture in the center of the billet are effectively suppressed.