This paper describes isolation and elucidation structure of the components from leaves and evaluate the radical scavenging activity on DPPH radical for antioxidant effect. Bioassay guided fractionation of MeOH extract afforded active EtOAc and BuOH factions. The most active EtOAc fraction was repeatedly chrormatographed over silica and Sephadex LH-20 to afford six flavonoid compounds. Studies on the antioxidant activity of these constituents showed that quercetin was the most active of these compounds. Luteolin and kaempherol are also active, These results suggested that the antioxidant activity of leaves of Angelica gigas may be due to flavonoid components. All the compounds were identified by spectroscopic methods and are the first report from leaves of Angelica gigas.