PROBLEM TO BE SOLVED: To provide an antioxidant agent widely applicable in the field of external preparations for the skin.SOLUTION: The antioxidant agent and the external preparation for the skin includes extracts of plants in the family of Maianthemum dilatatum. The antioxidant agent and the external preparation for the skin having an excellent effect is obtained by including one kind or not less than two kinds of plants in the family of Maianthemum dilatatum or their extracts.