PROBLEM TO BE SOLVED: To provide a method for effectively utilizing leaves of Japanese knotweed having a vitalizing agent function for enhancing the amount of exercise. SOLUTION: A dried powdery substance of Japanese knotweed leaf, which is characterized by using Japanese knotweed leaf. A dry powdery substance of Japanese knotweed leaf, which contains at least the following components (a) to (d). (A) Neochlorogenic acid (b) Chlorogenic acid (c) Rutin (d) Quercetin. A composition for improving motor function, which comprises a dry powdery substance of Japanese knotweed leaf as an active ingredient. [Selection diagram] None【課題】運動量を増強させる活力剤機能のあるイタドリの葉の有効利用方法の提供。【解決手段】イタドリの葉を用いたことを特徴とするイタドリ葉の乾燥粉状物質。少なくとも下記（ａ）～（ｄ）の成分を含有することを特徴とするイタドリ葉の乾燥粉状物質。（ａ）ネオクロロゲン酸（ｂ）クロロゲン酸（ｃ）ルチン（ｄ）ケルセチン。イタドリ葉の乾燥粉状物質を有効成分として含有することを特徴とする運動機能改善用組成物。【選択図】なし
