To provide a method and apparatus for collecting metallic impurities on a wafer periphery as a pre-treatment means for quantitatively analyzing only pollution metallic elements deposited on the wafer periphery, the elements which could not be quantitatively analyzed in the prior art.

After a wafer has been held vertically by a rear-side suction on a rotating member 26, the wafer is at its periphery immersed in an immersion container having a chemical solution therein. In this condition, the wafer is held or rotated to decompose and collect traces of metallic impurities on the wafer periphery into the chemical solution. Thereafter the traces of metallic impurities in the chemical solution are analyzed quantitatively by a flameless atomic absorption analyzer or an inductively coupled plasma mass spectrometer. As a result, it becomes possible to quantitatively analyze only pollution metallic elements deposited on the wafer periphery, for which it has not been possible to perform quantitative analysis in the prior art.