The dicing machine has a shielding plate movably arranged between a processing part and a microscope so as to check mist and spray produced from the processing part. The shielding plate can be moved back and forth between a shielding position and a retreated position, so that the shielding plate is positioned at the shielding position during processing of the work and at the retreated position when the operator replaces the old blade with a new one. Thus, even if the dicing machine has two spindles facing to each other, the shielding plate does not interfere with replacement of blades on the spindles.