The antioxidative activities of the fungus Eurotium sp. isolated from “Tenobesomen” were examined on cotton seed, corn and fish oils which were coated on “Tenobesomen” and oxidized during autoclave for 15 minutes at 120°C. The peroxide value (PV) of all oils treated with fungus Eurotium sp. were increased in the initial 1 day, then rapidly decreased to almost no PV counts within 6 days. This powerful antioxidative activities of fungus Eurotium sp. were shown for more than 2 weeks. From the results of PV of methyl oleate under oxidation, the similar antioxidative activities were also shown in the case of refined water extracts from medium with fungus Eurotium sp. cultivated at 2 weeks.