In this study, we are going to compare the chemical composition of the precipitation that falls in the Dangjin and Anmyon-do areas by analyzing the water soluble components (anion and cation). We also examined the effects of seasonal change and regional difference in those data sets. The [$NO_3;^- ;+;SO_4;^{2-}$] at 49.2${mu}$eq/l is 67% of the total anion of 73.1${mu}$eq/l, while that of [$NH_4;^+;+;Ca^{2+}$] at 37.7${mu}$eq/l is 62% of the cation in Dangjin area. Also, the [$NO_3;^-;+;SO_4;^{2-}$] concentration of 151.8 (${mu}$eq/l) is 62% for the total anion of 143.5 (${mu}$eq/l), and the [$NH_4;^+;+;Ca^{2+}$] concentration of 119.7 (${mu}$eq/l) is 47% for the cation of 254.3 (${mu}$eq/l) in Anmyon-do area. The ion composition ratio is shown for the order by 22% of $SO_4;^{2-}$, 20.8% of $NH_4;^+$ and 15.4% of $Cl^-$ that is the sum of 58.7% for the total ion composition in Dangjin area, and is the order by 33.8% of $NH_4;^+$, 16.3% of $SO_4;^{2-}$ and 11.1% of $Cl^-$ in Anmyon-do area. Furthermore, We predicted that even areas which were previously clean will get acid rain if there is large scale construction there or nearby.