PROBLEM TO BE SOLVED: To provide an agent for suppressing or preventing the oxidation of organisms comprising one or more extracts of materials selected from fungi belonging to the genus Ganoderma and truffle. SOLUTION: The agent for suppressing or preventing the oxidation of organisms contains one or more extracts of materials selected from fungi belonging to the genus Ganoderma and truffle. The agent for suppressing or preventing the oxidation of organisms and containing one or more extracts of the fungi belonging to the genus Ganoderma and truffle has excellent stability and exhibits excellent action to suppress or prevent the oxidation of organisms.
