To obtain an antioxidant capable of exhibiting effectiveness for prevention of the oxidation of lipid components of skin, oxidation damage to skin and skin aging by adding the antioxidant to a cosmetic, etc., comprising an extract of a specific plant known as a Japanese and Chinese medicine as an active ingredient.

This antioxidant comprises an extract of Leonurus sibiricus as an active ingredient. Leonurus sibiricus (flower, fruit, leaf, stem, skin, root, etc.) is extracted with a solvent such as a polar solvent, e.g. water or a lower alcohol or chloroform or dichloroethane to give an extracted solution, which is used as it is as the extract of Leonurus sibiricus or an essence obtained by concentrating the extracted solution or the residue obtained after removal of impurities from the essence is used. The amount of the extract of Leonurus sibiricus blended is 0.00001-5.0wt.%, preferably 0.00005-2.0wt.% calculated as a dried substance. Anti-oxidizing effects are exhibited by the blended amount. A cream, a lotion, a milky lotion, a shampoo, a rinse, etc., may be cited as the object to be mixed with the antioxidant.