PROBLEM TO BE SOLVED: To provide a slitter device which can be used for applying a correcting force surely opposing to a force applied to a corrugated fiberboard sheet in its width direction by a moving slitter knife, to the corrugated fiberboard sheet when properly regulating the trim width of the corrugated fiberboard sheets. SOLUTION: A slitter scorer 10 which performs rule line processing in the travelling direction of a corrugated fiberboard sheet 1 and also cuts the corrugated fiberboard sheet 1 in its travelling direction, is constituted so as to be equipped with a supporting member 13 equipped movably in the width direction of the corrugated fiberboard sheet 1, the slitter knife 11 supported by the supporting member 13 and movable in the sheet width direction with respect to the supporting member 13, and a sheet guide device 30 supported by the supporting member 13 on the upstream side in the sheet travelling direction from the slitter knife 11, and regulating the movement in the width direction of the travelling corrugated fiberboard sheet 1 when the supporting member 13 moves in the width direction of the sheet. COPYRIGHT: (C)2008,JPO&INPIT