PURPOSE: To facilitate positioning of both an excitation primary particle ray and a sputtering ion beam in a particle-ray analyzer which can be rapidly and easily used.

CONSTITUTION: A sample 2 placed on a stage 1, is used directly. A movable opening plate 5 having an opening 4, is positioned over the sample 2. When an electron beam is caused to irradiate the sample 2 after passing through the opening 4, a sample current flows through the sample 2, which is determined with an ampere meter 6. By fixing the opening plate 5 at the point when the sample current becomes maximum, the center line of the electron beam is positioned. Next, in the same manner as in an electron beam, an ion beam is caused to irradiate the sample 2 after passing through the opening 4, a sample current flowing through the sample 2 is determined, and the ion beam is fixed when the sample current becomes the maximum level. By the means mentioned above, the center line of the electron beam is caused to coincide with that of the ion beam.