PURPOSE: To prevent a dog bone and width reduction and to form a rolling material into an accurate and excellent shape by restricting a material to be rolled by a pair of horizontally shifting work rolls and a pair of vertical rolls shifting horizontally and vertically on the plane of work-roll axes.

CONSTITUTION: A pair of horizontal work rolls 2-1, 2-2 pressed by a pair of horizontal backup rolls 3-1, 3-2, are horizontally shifted by a shifting mechanism having hydraulic cylinders 12-1, 12-2. Further, vertical rolls 8-1, 8-2, supported by said mechanism and shifted by hydraulic cylinders 11-1, 11-2, are shifted vertically and horizontally in a state close to the horizontal work rolls 2-1, 2-2. A material 1 to be rolled is rolled in a state of being restricted from four sides by these four rolls. Accordingly, the side-end edges of material are regularly formed and its camber is also prevented without producing a dog bone and width reduction, and a material is formed into an accurate and excellent shape.