PURPOSE: To precisely split a mold along cracks at the respective intersecting points and ends of grooves when the cracking of a green sheet after firing is performed along the grooves by a method wherein the intersecting points and ends of lattice-like projecting parts of a punch are made higher than their remaining parts.

CONSTITUTION: A punch 11 consists of a main body 12 and lattice-like projecting parts 13 provided on its rear surface. The respective intersecting points 14 and ends 15 of respective projecting parts 13 are made higher than the remaining parts of the projecting parts 13. The punch 11 is elevatably mounted in a top force 17 and is imparted with downward pressing force with a spring 18. When the top force 17 is lowered under the state that a green sheet 20 is placed on a bottom force 19, firstly the punch 11 fixes the green sheet 20 by pressure so as to work grooves 21 by press. When the top force 17 is further lowered, the punch 11 compresses the spring 18 so as to fix the green sheet 20 by pressure, resulting in lowering the top force 17 so as to cut off the green sheet 20. Thus, since the grooves 23, the intersecting points 21 and the ends 22 of which are formed deeper, are produced on the pressed green sheet 20, the green sheet can be precisely cracked after firing.