PROBLEM TO BE SOLVED: To provide an active ingredient-containing particle that achieves both its absorption into a living body and its persistence, and also has excellent shape retention (storage stability, as well as durability such as solvent resistance and heat resistance).SOLUTION: A particle comprises a first fraction comprising an active ingredient and a second fraction comprising a surfactant, and has a number average particle diameter of 1 to 100 nm.SELECTED DRAWING: None【課題】体内への吸収性と持続性の両方を兼ね備え、かつ形状保持性（保存安定性、さらには耐溶剤性及び耐熱性等の耐久性）にも優れる、有効成分含有粒子を提供する。【解決手段】有効成分を含有する第１画分と界面活性剤を含有する第２画分とを含み、且つ個数平均粒子径が１～１００ｎｍである、粒子。【選択図】なし
