PURPOSE: To improve the productivity of rolling by adjusting the roll gap of a rolling mill group and executing rolling to the sectional shape larger than the target, then executing forming and rolling to the size of the target circular section with a 4-roll type roller device.

CONSTITUTION: The 4-roll type roller rolling device which is pivotally supported with rollers 11, 12 and rollers 13, 14 respectively making a pair to face each other is disposed in succession of the final rolls of a rolling mill group which executes the rolling of the preceding stage. The rollers 11W14 are mounted via tapered cylindrical roller bearings 21, etc., to an eccentric sleeve 17 keyed to a shaft 16. The roll gap of a finishing pass, leader pass, etc., is adjusted and the rolling reduction to the sectional area larger than the target sectional area is executed in the roller mill group of the preceding stage, then the molding to the target shape is executed with this 4-roll type roller rolling mill. Since this method is made to deal with production of diversified kinds and small quantity by using the common calibers of the rolling mills, the productivity is improved to a greater extent.