PURPOSE: To form efficiently a shape bar without wasting materials by using a flat roll and a sectional roll having partially different outer diameters in roll- forming a shape bar.

CONSTITUTION: A blank material is passed through the 1st set of rolls, to roll its part 11, to be rolled into a thin-thickness part in the width direction, by large- diameter rolls 211, 213 of a sectional roll 21. At that time, a large part of the flow of material moves to the side of a part 12 which is not subjected to rolling reduction, and is absorbed in a space 215 formed by the rolls 211, 213 and a roll 212 without causing the buckling of material. The rolled blank material 13 is passed through a pair of flat rolls 31, 32 to roll the part 12 into a flat one, thereby forming a shape bar 14. The bar 14 is passed between a flat roll 43 a grooved roll 41 having a groove 42, to form a shape bar 15 having a small cross section.