The natural antioxidant such as e-tocopherol and synthetic antioxidant BHT were used to compare antioxidative effects of those antioxidants from the physico-chemical properties and fatty acid composition changes in the soybean oil due to number of frying. The composition of frying oil were consisted of a group(Fresh oil), B gorup(Fresh oil added with 0.05% ${alpha}$-tocopherol), C group(Fresh oil added with 0.2% ${alpha}$-tocopherol), D group(Fresh oil added with 0.1% BHT), E group(Tocopherol removed oil from oil by active alumina column chromatography The results obtained were as follws : 1. The color was determined by the Lovibond colorimeter color intensity increased number of frying oil. 2, The acid value, TBA value and Carbonyl value were increased number of frying oil. 3. Natural antioxidants less effective than BHT but effect of ${alpha}$-tocopherol was very similar to that of BHT. 4. The order of antioxidative effect was 0.1% BHT, 0.2% ${alpha}$-tocopherol, 0.05% ${alpha}$-tocopherol, fresh oil, tocopherol remove oil.