To reduce the time required for an order change and to enhance a cooling performance, eliminating a holding guide for a rolling material.

A plurality of rolling apparatuses 10 respectively comprising two rolling mills 13, 15 is disposed along with a pass line PL of a rolling material 11 at predetermined intervals. Rotating axes of first reduction rolls 12, 12 of a first rolling mill 13 and second reduction rolls 14, 14 of a second rolling mill 15 are displaced at an angle of 90° with respect to each other, and each rotating axis of the reduction rolls 12, 14 inclines at an angle of 45° against a horizontal face. A roll caliber of the second rolling mill 15 at the downstream side shall be a round caliber. A distance between the axis of the first reduction roll 12 of the first rolling mill 13 and the axis of the second reduction roll 14 of the second rolling mill 15 is set to not more than 1.2 times of the diameter of the reduction roll 12. A cooling trough 18 is arranged at the side of an outlet of the rolling material 11 fed from each of the rolling apparatuses 10.