PROBLEM TO BE SOLVED: To provide a material which can be utilized pharmaceutically in a disease accompanied by overexpression of Id protein.SOLUTION: A method for producing an expression inhibitor of gene for coding Id protein includes a step of heating uronic acid-containing solution together with at least one kind of acid selected from a group comprising hydrochloric acid, sulfuric acid and citric acid.COPYRIGHT: (C)2014,JPO&INPIT【課題】Id蛋白の過剰発現を伴う疾患において医薬利用が可能な物質の提供。【解決手段】ウロン酸含有溶液を、塩酸、硫酸およびクエン酸からなる群より選択される少なくとも1種の酸とともに加熱することを含む、Id蛋白をコードする遺伝子の発現抑制剤の製造方法。【選択図】なし