PURPOSE: To obtain multiple pieces of steel bars by specifying the angle of inclination of plural ovals enclosed with upper and lower slit rolls and using the slit rolls having the angle of inclination inclined in the same direction.

CONSTITUTION: The rolled steel material having the section formed so as to make the respective sectional areas after dividing equally is introduced to the slit rolls before five passes from the final caliber. The plural oval calibers enclosed with upper and lower slit rolls are disposed with ovals g1, g2, g3 provided with 20° angle of inclination β to the centerline. The calibers are disposed with the angle β of inclination inclined in the same direction and the material is slit with the intermeshing edges having the inclination α during rolling with at least 10% draft. The material is further rolls respectively with the succeeding caliber rolls whereby plural or more pieces of steel bars are simultaneously obtd.