To provide a method which corresponds not only to enhancement in recent metallurgical technique but also to substantial improvements in the cleanliness of a metal material, such as steel or the like and high in reliability.

(N) sample pieces are collected from a metal material to be analyzed, and are electrolyzed to obtain residues, and these residues are elutriated to separate impurities contained in respective sample pieces and the maximum diameters aj (j=1, n) of impurities are measured with respect to (n) sample pieces and the estimated maximum diameter amax of the impurities contained in the metal material to be analyzed is calculated, to evaluate the cleanliness of the metal material to be analyzed.