PURPOSE: To increase the elongation in a groove of a first roll and to decrease the total number of roll stands by forming a hollow ingot to an elliptic shape just before advance into the first roll stand of a continuous-tube rolling mill.

CONSTITUTION: The hollow ingot is shaped to the elliptic shape without the decrease of its wall thickness just before the advance into the first roll stand of the continuous-tube rolling mill in such a manner that the clearance between a rolling mandrel and the inner surface of the hollow ingot in the region of a base of the groove of the rolls of the first roll stand is larger than the clearance in the region of the roll flanks. As a result, the elongation in the first groove may be increased and the total number of the roll stands may be decreased.