PURPOSE: To make the rolling deviations on an outlet side zero and to make plate thickness constant with one time of rolling by changing roll gaps in accordance with the deviation between set rolling load and actually measured rolling load thereby correcting the deviation.

CONSTITUTION: A rolling load deviation ΔP is determined from set rolling load P0 with respect to a target outlet side plate thickness h0 and actually measured rolling load P. In accordance with the deviation ΔP, a roll gap is changed by a roll gap correction rate ΔS. The secondary rolling load change ΔP2 to be generated by this change is determined in accordance with a coefft. K of plasticity, a mill constant M and a roll gap correction rate ΔS, and the load P is corrected by this change ΔP2.