PURPOSE: To remarkably reduce the deviation between the product width and the target width of a steel sheet by acceleration rolling in a finish rolling stage.

CONSTITUTION: By completing the finish rolling of the steel sheet 7 at a temp. higher than the transformation temp. Ar3 and adjusting tension to be imparted to the steel sheet 7 between a coiler 11 and a finishing mill 9, the rate of decrease in the width of the steel sheet 7 is adjusted. The adjustment of the tension to be imparted to the steel sheet 7 is executed by preliminarily determining a tension imparting pattern to the steel sheet 7 for every product size and for every kind of steel based on a width decreasing pattern in the longitudinal direction of the steel sheet 7 and relationship between the tension to be imparted to the steel sheet and the shrinkage amount of width, or executed by measuring the width of the steel sheet 7 just after finish rolling, determining the deviation between this measured value of width and the target thickness of the steel sheet 7 and based on the relationship between the tension to be imparted to the steel sheet 7 and the decrease amount of width of the steel sheet 7 which are predetermined for every product size and for every kind of steel.