PURPOSE: To uniformize a surface pressure of a rolling roll, to prevent a damage of the roll and to improve the durability of the roll by expanding at least a part of a sectional form of a hole die to form in unsymmetrical form at working area of the rolling roll to reduce a rolling reduction of a pipe material at this position.

CONSTITUTION: The pipe 17 to be rolled at the working area of the hole die 14 is rolled expanding both the sides 17b, 17b at both side relief parts with respt to the rolled part 17a, 17a by each surface 12a, 13a of each groove 12, 13. At this sectional position, the pipe 17 is rotated by a prescribed angle of 60° in an arrow direction C in the succeeding rolling stage. Then, each expanded part 17b, 17b of the pipe 17 is faced to the expanded positions 12b, 13b of each groove 12, 13 respectively, and at these positions 12b, 13b, the rolling reduction rate rolled at each position 12b, 13b is reduced.