PURPOSE: To constantly control the irradiation intensity of pulse laser so as to improve the controlling stability in a laser sampling analyzer where a fixed specimen is gasified by applying pulse laser light.

CONSTITUTION: After an He-Ne laser beam (reference light) 3 is amplitude- modulated by a modulator 31, it is applied onto a fixed specimen 12 through a lens 8 in such a manner that its light axis may be aligned with that a YAG laser beam (pulse laser light), and the position of the lens 8 is regulated by comparing the phases of the reflected light and the amplitude-modulated signal by a phase detector 33, so that the distance between the lens 8 and the specimen 12 may be kept constant. On the other hand, the output light intensity of the YAG laser beam 1 is controlled according to the phase comparison result, thereby stabilizing the intensity of the beam applied to the specimen 12.