Provided is a surface processing agent capable of improving touching feel in usage as well as giving excellent water-resistance and oil-resistance.The surface processing agent is characterized by containing an organosiloxane derivative which is represented by the following general formula (1) or the following general formula (3), which is a divalent or trivalent metal salt of the terminal carboxyl group.本發明提供一種除了改善使用觸感之外,同時可賦予優越耐水性、耐皮脂性之表面處理劑。該表面處理劑之特徵係:含有下述通式(1)或下述通式(3)表示之末端羧基之2價或3價金屬鹽之有機矽氧烷衍生物。