PURPOSE: To prevent the occurrence of burr and blurr by vertically a little adjusting a chock supporting a cutter shaft by a taper member to control the depth of cut for material to be cut, so that nipping and reverse shearing are caused by rolls in the next process.

CONSTITUTION: Taper members 15, 16, 17, 18 are slid to change the thickness between the taper members, and chocks 11, 12 are moved up and down in heads 9, 10 to set the clearance between a lower cutter 13 and an upper cutter 14 to about 20W30% of board thickness. Secondly, a motor 27 is driven to rotate screw shafts 21, 22 through a speed reducer 26 and bevel gears 24, 25, and thrust is generated in portions of female screws 28, 29 to move the heads 9, 10 in the direction of an arrow A, so that a plate 31 on a roller table 30 is cut to half. While the plate is transported, such cutting work id done. Thus, sequentially half-cut plates 31 are pressed by rolls disposed on the outlet side and reverse-sheared to be separated.