In the dicing machine, a flange cover with which the blade is covered is divided into two, and the first cover is openable. An interlock device is provided so that a blade attaching and detaching device cannot be attached when the first cover is at the closing position, the first cover cannot turn to the closing position when the blade attaching and detaching device is attached, and the processing of the work is not started when detected luminous energy of a blade breakage detector, which is attached to the first cover, is not reduced by a predetermined amount. Thus, the blade and the work are prevented from being damaged by processing the work without applying coolant, the mechanism of the dicing machine and the blade attaching and detaching device are prevented from being damaged by operating the dicing machine without detaching the blade attaching and detaching device, and the work is prevented from being unprocessed but sent out by operating the dicing machine without attaching the blade.