To provide composite particles improved in a solubility by hydrophilizing hydrophobic amino acid, and a method for producing the same.SOLUTION: The present invention provides hydrophilic composite particles comprising a plurality of hydrophilic and hardly water-soluble child particles and hydrophobic amino acid mother particles coated with a plurality of the child particles； and a method for producing composite particles comprising a step (a) of introducing hydrophilic and hardly water-soluble child particles and hydrophobic amino acid mother particles into a carbon dioxide liquid, a step (b) of irradiating the carbon dioxide liquid with an ultrasonic wave, a step (c) of migrating the carbon dioxide liquid from a liquid state of the carbon dioxide to a supercritical state of the carbon dioxide without passing through a gaseous state, and a step (d) of migrating the carbon dioxide from the supercritical state of the carbon dioxide to the gaseous state without passing through the liquid state to remove the carbon dioxide to obtain the composite particles.SELECTED DRAWING: Figure 3【課題】疎水性アミノ酸を親水化させて溶解特性を向上させた、複合化粒子及びその製造方法の提供。【解決手段】親水性かつ水難溶性の複数の子粒子と、前記複数の子粒子で被覆された疎水性アミノ酸母粒子とを含む、親水性の複合化粒子。（ａ）二酸化炭素液体中に、親水性かつ水難溶性の子粒子及び疎水性アミノ酸母粒子を導入する工程、（ｂ）前記二酸化炭素液体中に、超音波を照射する工程、（ｃ）前記二酸化炭素液体を、二酸化炭素の液体状態から気体状態を経由することなく二酸化炭素の超臨界状態に移行させる工程、（ｄ）前記二酸化炭素を、二酸化炭素の超臨界状態から液体状態を経由することなく気体状態に移行させて、前記二酸化炭素を除去して複合化粒子を得る工程、を含む、複合化粒子の製造方法。【選択図】図３
