Oleoresin, 6-gingerol and 6,10-gingerol: 6-paradol＝ 1 : 1 mixture were extracted from ginger (Zingiber officinale Roscoe) and changes of its antioxidant activity by heat-treatment were studed. Oleoresin was extracted with Ethanol-Ether and 6,10-gingerol : 6-paradol(1 : 1) and 6-gingerol were extracted with Hexane and Hexane : Ether＝1 : 1, respectively, and identified on the Thin-layer Chromatograpy (TLC) plate with the solvent system of Hexane : Ether(1 : 4, v/v). And oleoresin was heat-treated during 0, 10, 30, 60, 120 minutes, and 6-gingerol and 6,10-gingerol : 6-paradol＝1 : 1 were heat-treated during 0, 5, 10, 20, 40 minutes, respectively, at 140℃ dry oven. To compare with antioxidant activity, oleoresins were added into soybean oil at 3% level, 6-gingerol and 6,10-gingerol: 6-paradol＝1 : 1 at 0.1% level, BHT and TBHQ at 0.02% level, respectively. All the substrates treated were stored in a incubator at 45.2℃ condition. The oxidative stability was estimated by the analysises of peroxide value and conjugated diene value during storage. The results were as follows: Antioxidant activity of oleoresins were considerably high and by heat-treatment were not decreased. 6-paradol was not show the antioxidant activity. 6,10-gingerol: 6-paradol＝1 : 1 provided poor protection for soybean oil. Antioxidant activity of 6-gingerol was higher than 6,10-gingerol : 6-paradol＝1 : 1 and by heat-treatment antioxidant activity was directly decreased. Relative antioxidant effectiveness(RAE) of each antioxidant was compared. RAE was found to decrease as follow : TBHQ>oleoresin≫BHT TBHQ≫BHT> 6-gingerol≫6,10-gingerol : 6-paradol＝1 : 1