PROBLEM TO BE SOLVED: To provide a hair treating agent which can simply and quickly impart body and stiffness to hair fibers, especially to hair not having the body and the stiffness, to provide a hair-modifying agent, and to provide a hair-modifying method.SOLUTION: This hair-modifying agent comprises a hair-treating agent (A) and a hair-treating agent (B) for accelerating hydrolysis or polymerization reaction. The hair-treating agent (A) contains a carboxyl group-having alkoxysilane. And the method for modifying the hair comprises coating the hair with the hair-treating agent (A) and then coating the hair with the hair-treating agent (B).COPYRIGHT: (C)2008,JPO&INPIT【課題】毛髪繊維、特にハリ・コシがない毛髪に対し、短時間かつ簡便に優れたハリ・コシを付与することができる毛髪処理剤、毛髪改質剤及び毛髪改質方法の提供。【解決手段】カルボキシ基を有するアルコキシシランを含有する毛髪処理剤(A)。当該毛髪処理剤(A)、及び(B)加水分解又は重合反応の促進のための毛髪処理剤からなる毛髪改質剤。上記毛髪改質剤を用い、毛髪処理剤(A)を毛髪に塗布した後、毛髪処理剤(B)を毛髪に塗布する毛髪改質方法。【選択図】なし