PROBLEM TO BE SOLVED: To provide a skin penetration promoter capable of remarkably improving the penetration of a hydrophilic physiologically active substance into the skin. SOLUTION: The skin penetration promoter of a physiologically active substance having a LogP of −5 to 0 and containing a polyoxypropylene methylglucoside represented by the formula [I] is used. (The meanings of the symbols in the formula are as described in the specification.) [Selection diagram] None【課題】親水性の生理活性物質の皮膚への浸透性を顕著に向上させ得る皮膚浸透促進剤を提供する。【解決手段】式［Ｉ］で表されるポリオキシプロピレンメチルグルコシドを含有する、ＬｏｇＰが－５～０である生理活性物質の皮膚浸透促進剤とする。（式中の記号の意義は、明細書に記載の通りである。）【選択図】なし
