PURPOSE: To prevent plate width edges from splitting in the following rolling process by shearing the plate width edges with a shearing cutter inclined in relation a to plate so as to form the cross section after shearing into a trapezoid.

CONSTITUTION: The shearing cutters 3 and 4 at both sides are arranged, being inclined in relation to a plate 1, on right and left frames 2a and 2b. The shearing cutters 3 and 4 are connected to motors 5a and 5b through transmission 6a and 6b respectively. The shearing cutters 3 and 4 are rotated to shear the width edges of the plate 1 diagonally feeding the plate 1 of which the cross section is trapezoid to the following rolling process. The diagonal shearing of the plate width edges allows the expansion of the plate width edges in the following rolling process to be proper preventing the edge from splitting.