This study was carried out to investigate the structure of antioxidative constituents and the free radical scavenging effect of the main ingredients from Galla Rhois(Rhus javanica Linne). Antioxidative activities of n-hexane, EtOAc and BuOH extracts of Galla Rhois were similar or even higher than that of natural (tocopherol) or synthetic antioxidant (BHA). It is suggested that major fractions for the antioxidative activity of Galla Rhois were the n-hexane, EtOAc and BuOH extract compartments. In the subsequently experiment, one active compound from n-hexane extract, three active compounds from EtOAc extract and one active compound from BuOH extract were isolated. Their chemical structures were identified as syringic acid, protocatechuic acid, gallic acid methylester, gallic acid and $1,2,3,4,6- penta-O-galloyl-{eta}-D-glucose$ on the basis of the speculation of spectral data and chemical reaction. Among the compounds, protocatechuic acid, gallic acid methylester and $1,2,3,4,6- penta-O-galloyl-{eta}-D-glucose$ showed most potent radical scavenging effect using DPPH method.