Effects of Oplopanax elatus have known to various pharmaceutical therapies. However, chemical prosperities in the plant are rarely investigated. In order to detect biological activity, we evaluated the antioxidant activity of five fractions from methanolic extracts in each part of O. elatus. Also, contents of polyphenols and polysaccharides were measured. Five fractions were of sub-fractions using n-hexane, ethyl-acetate, n-butanol, and water from methanolic extracts. Ethylacetate and n-butanol fractions from stem and root exhibited strong antioxidant activity and high total phenolics content. On the HPLC analysis, ten free phenolics, including p-hydroxybenzoic acid, chlorogenic acid, caffeic acid, syringic acid, p-cou maric acid, ferulic acid, naringin, hesperidin, quercetin and trans-cinnamic acid, were identified from the fractions and were shown to different quantitative proportions. Furthermore, ethylacetate and n-butanol fraction had the highest amount of chlorogenic acids, one of the cinnamic acid derivatives possessing pharmacological properties. These results indicated that the fractions of O. elatus, as well as methanolic extracts, could be used as natural antioxidative ingredients.