PURPOSE: To eliminate an excessive action of a rolling-down motor due to eccentricities of rolls of the front stage, and to highly accurately control the sheet thickness, by averaging the sheet thicknesses of a material to be rolled detected by an inlet-side thickness gauge throughout a peripheral length of said roll, and controlling a rolling reduction basing on the average value.

CONSTITUTION: In the case of a feed forward AGC, for instance, a sheet 1 to be rolled running in the direction of the arrow is cold-rolled by a rolling mill 2. A memory 4 stores the thickness data detected by a thickness gauge 3 and shifts said data by one digit at every pulse outputted from a pulse generator 10. An arithmetic circuit 5 reads out from the memory 4, the stored data of the latest i.e. 1WL/P digits about a part of the sheet 1 having the length equivalent to the peripheral length L of a roll of the front stage, and computes the average value of the lengths L. As the position shifted from the point just below the thickness gauge 3 to the mill side by L/2 is the center of a part of the sheet 1 which is an object of computing, the value A is set as the value representing said position. Thus the controlling is performed by means of the feed forward system, by using the value A as information of a rolling-down position controlling.