PURPOSE: To enhance analytical accuracy by reducing a number of defects on the surface of a specimen and to attain to shorten a preparation time while achieving the reduction in the number of analytical processes, by mixing and crushing a specimen such as an ore or slugs and a binder material in such a state that the mixing ratio of both of them is set to a specific range.

CONSTITUTION: In preparing a specimen by mixing a binder material with a specimen for fluorescent X-ray analysis, the binder material is mixed with the specimen in a range of 1/2,000W1/1,000 on a wt. basis while the resulting mixture is crushed and subjected to compression molding to obtain a smooth and homogenous X-ray irradiation surface. At this time, the analytical specimen changes corresponding to the mixing ratio with the binder material and a good result is obtained by bringing the mixing ratio to 1/1,000 or less in order to adjust analytical accuracy to about 0.3W0.4% or less. Therefore, the mixing ratio is well if 1/700 or less, pref., 1/1,000 or less while the mixing ratio of 1/2,100 or more, pref., 1/2,000 or more is an optimum range from the aspect of the generation frequency of a surface defect.