PROBLEM TO BE SOLVED: To provide a skin external preparation suitable for preventing or ameliorating aging, and ameliorating wrinkles.SOLUTION: The skin external preparation includes an extract obtained from plants belonging to genus Equisetum, family Equisetaceae as an ingredient having a hyaluronic acid production-promoting action in epidermis or dermis, particularly an ingredient increasing production amount of high molecular weight hyaluronic acid. Also the hyaluronic acid production-promoting factor has the hyaluronic acid production-promoting action in epidermis or dermis via epidermis.