To detect a precise sheet shape by correcting a shape detection signal in a sheet edge portion during cold-rolling of a flat sheet, and to control the shape from the sheet shape detection data so as to manufacture the rolled sheet of the target shape in a superior shape precision and in a high productivity.

When each segment 21 of a shape detection roll 20 detects a load received from a rolling sheet and detects the shape of the rolled sheet by treating the detection signal, the detection signal, from a sensor corresponding to the segment 21 whose entire face is not covered by the rolled sheet, is treated correcting the signal using a sheet covering ratio (A/B) of the segment and thus the sheet shape under rolling is detected. The detected shape is compared with the target shape and a sheet shape control means is adjusted so that the sheet shape approximates to the target shape.