A laser processing unit principally includes a pulse oscillation solid-state laser apparatus with laser diode as the excitation source, wherein laser diode emitting a beam in a main energy absorption band of a solid-state laser active medium and includes an admeasuring apparatus, measuring the radiant laser output in the complete time; a maximum judge device, obtaining the maximum of the laser output value measured in the special monitoring cycle at the same time of radiating the laser beam; an error judge device, comparing the maximum and the special laser output value as the monitoring level after some time in the scheduled given monitoring cycle, and judging whether the maximum is in the special range; and a failure process apparatus, displaying the alarm content and at least stop the operation of the pulse oscillation solid-state laser apparatus simultaneously when the error judge device judges the maximum is beyond the special range. |