A composition for external use, comprising 2-O-(.beta.-D-glucopyranosyl)ascorbic acid represented by the formula (I): or a salt or ester thereof which is safe to the human body, and a koji mold or a processed koji. The composition for external use is excellent in skin permeability, containing an ascorbic acid derivative which is excellent in stability, utilized persistently in the living body, and strong in antioxidant activity, and has little skin irritation.