PURPOSE: To improve the shape accuracy of a rolling material by raising the electric current of a motor by a prescribed quantity at the estimated time and preventing the lowering of a rolling speed caused by the biting of crop.

CONSTITUTION: A load detector 5a detects that the rear end of a rolling material 2 passes the 1st rolling rolls 9a, to start a counter housed in a main control device 15. The counter is set, by a setter 18a, to the timing when the rear-end crop of material 2 is bitten by the 2nd rolling rolls 9b. At the time of counting up with respect to a set value in the inside of control device 15; an electric current compensating value 19, set by a compensating-current setter 17b, is inputted to an electric current controller 13, to compensate the lowering of the number of revolutions of a motor 7b. The balance of speed at the 2nd stand and the 3rd one is compensated by this method, and an unneccessary tension is prevented from acting on the material 2. Tjis procedure is applied in sequence, and the shape accuracy, such as the diameter in the longitudinal direction of material 2, is improved.