In various experimental results were showed that organic compounds have an important fraction from 10 to 70% of the total aerosol mass. Organic carbon contains water-soluble organic carbon (WSOC) and water-insoluble organic carbon(WISOC). WSOC is involved in the most unknown liquid-phase chemistry of wet aerosol and clouds. It is also worked as cloud condensation nuclei (CCN). Formation of secondary organic aerosol by chemical reaction of hydrocarbon compounds is a source of the main pollution of WSOC compounds. In this study, Particle-into-liquid sampler (PILS) coupled with total organic carbon (TOC) analyzer and ion chromatography (PILS-TOC-IC), was used for semi-continuous measurement of WSOC and ionic compounds of PM2.5 during April-June 2016 at Baengnyeong Island Atmospheric Research Center, operated by the Korea National Institute of Environmental Research (NIER) and the Bukhansan national park during July through September 2017. In the period above Korea air quality standard at baengnyeong island, PM2.5, WSOC, nitrate, sulfate, and ammonium were increased to twice as the overall average value. And ionic compounds were increased 3.8 % in higher period than standard. WSOC/OC ratio was 0.5±0.3 in Baengnyeong island that was higher than roadside and urban and lower than background site. The ratio of BC370nm/BC880nm was observed 0.93 during this measurement period. Therefore, Baengnyeong island has primary emission of OC as well as the formation of secondary aerosol by photochemical or chemical reaction. From the comparison with ionic components, this result was indicated that ambient air of Baengnyeong island was neutralized because ammonia gas was sufficient to generate ammonium sulfate or ammonium nitrate from reaction with sulfuric acid or nitric acid. The timeline of aerosol chemical compositions reveals a strong influence from an urban area (Seoul) at the site in Bukhansan National Park. Inorganic aerosol composition was observed to be dominated by ammoniated sulfate at most times with ranging from 0.1 ? 32.6 μg/m3 (6.5 ? 76.1 % of the total mass of PM2.5). The concentration of ammonium nitrate, a potential indicator of the presence of local source, ranged from below detection limits to 20 μg/m3 and was observed to be highest during times of maximum local urban (Seoul) impact.