A method for the quantitative estimation of characteristics of inorganic components in rain water is proposed. In this paper, the following relationships were studied : SO₄^2- vs. various cations ; NO₃^- vs. various cations ; and Cl^- vs. various cations. By stoichiometric analysis, the chemical forms and the sources of airborne materials in rain water were determined. Rainfall events on the Japan Sea side of Japan (Kanazawa) were analyzed and additionally compared with data for the Tokyo area (Kanto region). Some samples contained Cl^- released from anthropogenic sources as well as from maritime sources. The excess (non-maritime) Ca²⁺ in some samples still retained a correlation with maritime components, although other excess cations were almost independent of maritime components. Since the sum of NO₃^- and Cl^- (in meq/1) was approximately equal to that of NH₄⁺, Na⁺ and Mg²⁺, it was suggested that there was a mechanism to balance the anions and the cations. As a result, hydrogen ion concentration was expressed as a function of SO₄^2- and Ca²⁺ concentrations.