PURPOSE: To enable piercing and elongation continuously, at a large quantity and with poor surface flaws by using an inclined roll mill, spraying cooling water to the rolls from a mist nozzle, and/or removing excessive cooling water on the roll surfaces with a wiper.

CONSTITUTION: A billet, a bloom, a hollow tube stock 8 of austenitic stainless steel wherein component ranges in weight % are composed of ≤0.5% C, 0.1-5.0% Si, 0.1-5.0% Mn, 10-50% Cr, 3-50%Ni, 1.0-5.0 Mo, ≤0.01% S, ≤0.03% P, ≤0.03% O, 0.01-0.25% N, a content of each element satisfies an expression 1 and the balance is composed of Fe and unavoidable impurities are used. They are heated uniformly at a temperature zone 800-1300°C, then, cooling water to rolls 1 is sprayed from mist nozzles 2 and/or they are pierced or elongated by an inclined roll mill for removing excessive cooling water by wipers 6 from the roll surfaces.