To perform cutting processing with high precision by reducing the vibration of a work during cutting processing of the work.

A work W is placed on a table 23 which reciprocates along the right and left direction to a sawtooth. The work W is clamped by a clamp device 39 provided in a cutting width positioning device 41, the cutting width positioning device 41 moves forward to almost cross to a cutting line CL of a sawtooth in a right angle direction on the table 23 and the cutting position of the work W is positioned at the cutting line CL of the sawtooth. This positioned work W is surely placed under pressed condition on the table 23 by a work plate pressing device 103 near the cutting line CL on the table, and the table 23 is moved forward to the direction of the sawtooch to cut and process the work W. As the vibration of the work W during cutting operation is suppressed by the plate pressing device, the precision of the cutting processing can be improved and also the service life of the sawtooth can be lengthened.