PROBLEM TO BE SOLVED: To provide a triblock type co-modified organopolysiloxane enabling a PEG-free recipe to be designed as the whole recipe without damaging touch feeling-improving effects caused by a diglycerol derivative or a sugar-alcohol modifier because of extremely superior emulsification-dispersion properties in a liquid phase in simple use, and to provide an application thereof.SOLUTION: There is provided an organopolysiloxane co-modified with a 1-12C monovalent hydrocarbon group (with the proviso that the one having an oxyalkylene structure having average two or more repeat number of oxyalkylene units is excluded), and a sugar-alcohol group-containing organic group or a diglycerol derivative group having an average number of repeat glycerol units within the range of from 1.1 to 2.9. There are also provided a surfactant/dispersing agent, an emulsifier for a water-in-oil type emulsion, an external use preparation and a cosmetic composition comprising the organopolysiloxane.【課題】単独での油相中への乳化・分散性に著しく優れるため、ジグリセリン誘導体または糖アルコール変性基による感触改善効果を損なうことなく、処方全体として、PEGフリー処方を設計可能なトリブロック型共変性オルガノポリシロキサンおよびその用途を提供する。【解決手段】炭素原子数1~12の一価炭化水素基(オキシアルキレン単位の繰り返し数の平均値が2以上のオキシアルキレン構造を有するものを除く)、及び、糖アルコール基含有有機基またはグリセリン単位の繰り返し数の平均値が1.1~2.9の範囲内にあるジグリセリン誘導体基で共変性されたオルガノポリシロキサン。それを含有する界面活性剤・分散剤、油中水型エマルション用乳化剤、外用剤ないし化粧料。【選択図】なし