PURPOSE: To allow automatic control in the positional control of the rotary shaft of a spindle, stopping operation of a dicing apparatus, etc., by providing means for monitoring a blade in dicing process, and means for automatically controlling a spindle fixed with the blade.

CONSTITUTION: The dicing apparatus comprises a blade 1 for cutting a semiconductor wafer into a plurality of pellets, a flange 2 being employed as a holder when the blade 1 is fixed to a spindle 3, a sensor projecting section (or a camera) 4a for monitoring the blade 1 from lateral direction, a sensor light receiving section (or a camera) 4b, a wheel cover 5 mounting the sensors 4a, 4b, and means 6 for automatically controlling the spindle 3 based on an output from the sensor 4b.