PURPOSE: To accurately control synchronously both opening degree at the rough rolling and to stably roll the stock to be rolled while exactly guiding by operating 2-series side guiding devices while being linked.

CONSTITUTION: On the case of the rough rolling that the stock to be rolled is too thick to be wound up by the coiler, the feeding side guiding devices 6, 7 are set, 2 series together, to the opening degree of the stock to be rolled plus the prescribed value of dimension and the exit side guiding devices 6, 7 are set, 2 series together, to the opening degree of the width of the stock to be rolled plus the prescribed value of dimension. When the operation is shifted to the reverse pass after the one pass is finished, the opening degree is reversed and execute rolling. In such a way, the stock to be rolled is fed straightly to the rolling mill while being guided always with the feeding side guiding devices 6, 7 and is rolled.