PURPOSE: To obviate the fluctuation of a stop position caused by a fluctuation of a carrying load by measuring length, the number of pieces, and a surface temperature of a billet to be carried, deriving carrying torque from various data of the billet set in advance and executing horizontally feeding speed control of the billet by secondary resistance of a motor.

CONSTITUTION: An output of a steel detector 5b is inputted to a length measuring instrument 8 and length of steel is derived, and a temperature measured by a steel temperature measuring instrument 5d is inputted to a carrying torque arithmetic unit 10. An operator inputs in advance the relation of weight per unit length of a square billet, temperature and a sliding friction coefficient from a setting device. The carrying torque arithmetic unit 10 derives a ration of carrying torque and motor rated torque, outputs it to a secondary resistance selector 11, and the secondary resistance selector 11 selects a secondary resistance amount corresponding to the ratio and outputs it to a secondary resistance controller 12. The secondary resistance controller 12 operates a resistance short circuit contactor 14. Secondary resistance of a motor 3 is controlled to a prescribed amount through a resistor 13 by the resistance short circuit contactor 14.