To provide the impurity analyzing method of a silicon wafer for decomposing the whole part of even one silicon wafer, for condensing it in a short time, and for surely collecting impurity.

The whole part or one part of one silicon wafer is immersed in the mixed acid of oxygenated water and sulfuric acid, and immediately dissolved by steam to be generated due to the heating of the mixed acid of hydrofluoric acid and nitric acid, and the acquired solution is heated, condensed, and analyzed by a high frequency inductive coupled plasma mass spectrometry or an atomic absorption spectrometry.