To provide a method for controlling consumption amount of a cutting blade for exactly controlling the consumption amount of the cutting blade by utilizing laser beam to be irradiated on a groove bottom.

In this method, outgoing beam of a laser point 72 is set to pass a focus 76 of an imaging means, the laser beam 74 is projected in a cut groove made by cutting a workpiece by the cutting blade, and a reference position coinciding process for moving the imaging means in a height direction (Z-axis direction) so that a beam spot of the laser beam may coincide with the focus 76 of the imaging means at the groove bottom of the cut groove is performed. After properly cutting the workpiece by the cutting blade, a beam spot forming process and the reference position coinciding process are performed. The consumption amount of the cutting blade is determined from a difference between the position of the Z-axis direction of the imaging means after the reference position coinciding process executed previous time and the position of the Z-axis direction of the imaging means after the reference position coinciding process executed this time.