PURPOSE: To prevent the fault of device due to the failure of passing and excessive load by setting the position of either axial center of upper or lower eccentric sleeves in the front of an orthogonal plane and the position of the axial center of the other eccentric sleeve in the rear of the orthogonal plane.

CONSTITUTION: The axial center Q1 of the upper eccentric sleeve 10 is positioned by setting a prescribed separating distance ME in the front of the orthogonal plane Y in the rolling direction and the axial center Q2 of the lower eccentric sleeve 10 is positioned by setting a prescribed separating distance ME in the anti-rolling direction from the orthogonal plane Y. That is, both axial centers, Q1, Q2 are set at the position in diagonal relation to the point G where the orthogonal plane Y and the center position in the thickness direction of the web of material to be rolled are crossed. In this way, whichever of the forward or backward direction can be selected as the rolling direction without fear of adverse effect due to drawing-in force.