PURPOSE: To realize the highly accurate and speedy work and remarkably reduce the load of a worker by a method wherein a material to be worked is fixed with a clamp and the marking line written in ink of the material to be worked is read with a detecting means on a working cutter side so as to control an X-axis driving motor by stopping on the basis of the detection signal in order to perform setting work.

CONSTITUTION: When mortising is intended, under the state that the tip of a material to be worked W is controlled by being abutted against an abutting piece 31 for positioning on a seating stand 20, a pair of vise pieces are actuated from both the sides of the material to be worked W so as to fix it centripetally by clamping. Next, when positioning commands are given on a keyboard, an X-axis driving motor M2 is driven to the required horizontal direction so as to shift a working cutter S together with a detecting switch SW to the same direction in order to stop the movement of the cutter in X-axis direction when the marking line written in ink of the material to be worked W is detected. When mortising is intended, the material to be worked W is bridgingly supplied on a seating stand 25, the material to be worked W is fixed by being clamped with a lateral clamping means 26 under the state that the marking line (b) written in ink of the material W approximately coincide with the indicator line 32. By giving the positioning commands on the keyboard, the setting of the working cutter on the basis of the marking line written in ink is done.