PURPOSE: To adjust the engagement of punched blades of a sheet blank for manufacturing a case.

CONSTITUTION: A plurality of cutter bases 3, 3a are slidably arranged on parallel rotary shafts, respectively, and a connection plate 46 is fitted in a peripheral groove 31 provided at outer periphery of the cutter base 3 for the cutter bases 3, 3a which oppose in the vertical direction and form a pair in a condition in which there is room. A screw member 51 is screw-fitted in the connection plate 46 in the peripheral groove 31, and a lock nut 55 is screw-fitted in the screw member 51. A slide guide member 56 is provided between both ends of the screw member 51 and a side wall of the peripheral groove 31, and an engaging portion 53 for engaging rotary tool is formed on the screw member 51. By turning the screw member 51, the position of a cutter 6 can be easily adjusted to the optimum position where it engages with a cutter of the mating tool rest 3a in accordance with the tool rest 3.