Acid rain due to air pollution has been believed to be harmful to vegetation and crops, either by direct deposition on the foliage or by indirect leaching of nutrients from the soil. This study was conducted to investigate physiological response and damage of soybean caused by acid rain in the glasshouse at the experimental station of Seoul National University. Soybean (Glycine max L.) cv. Sinpaldal was subjected to simulated acid rain (SAR) two times a week from R2 stage until its maturity. The pH values of SAR treatments were ranged from 2 to 5 together with tap water treatment (pH 7±0.2) as a control. The SAR was composed of H2SO4 and HNO3 at the ratio of 2:1 (v/v). SAR treatment at pH 2 caused clear visual damage on leaves and pods with severe chlorosis and necrosis even after the first SAR was applied, while those at pH greater than 3 showed no clear visual damage. Chlorophyll content (expressed as SPAD value) tended to decrease with decreasing pH with significant reduction at pH 2 as compared with pH values greater than 3. Photosynthesis also showed decrease with decreasing pH with significant reduction at pH 3 and 2. Soybean yield and its components were also affected by SAR treatment, particularly significant at pH 2.