PURPOSE: To suitably control the opening and to prevent the edge parts from being ununiform or broken down by setting the opening of side guides in accordance with actual results of opening of the same kind of strip preceded at the start of coiling and setting it in accordance with the rotation of guide rolls after the start of coiling.

CONSTITUTION: The guide rolls 14 through which a rotational peripheral surface agrees materially to the guide surfaces of side guides 10 are equipped and at the start of coiling, an information of an opening obtained about the same kind of strip preceded is reflected to set the opening between the side guides 10. Consequently, the initial opening can be always set suitably. Then, after the start of coiling, the opening between the side guides is controlled in accordance with the rotation of the guide rolls 14. Therefore, the state shown when the edge parts of the strip A come in contact with the guide surfaces of both right and left side guides 10 can be equalized on the right and left.