There is provided an organopolysiloxane which is excellent in extensibility as well as solubility and dispersibility in water and lower alcohols. There is provided an organopolysiloxane with a poly(N-acylalkyleneimine) segment having a repeating unit represented by the following general formula (1):wherein R1represents a hydrogen atom or an alkyl group, an aralkyl group, or an aryl group each having 1 to 22 carbon atoms, and n is 2 or 3, wherein the segment is bound to each of at least two silicon atoms of an organopolysiloxane segment as a main chain via an alkylene group containing a hetero atom, wherein the number-average molecular weight of the segment is 800 to 1600, the mass ratio of the organopolysiloxane segment as a main chain and the poly(N-acylalkyleneimine) segment is 65/35 to 82/18, and the weight-average molecular weight of the organopolysiloxane segment as a main chain is 10,000 to 100,000.本發明提供一種延伸性以及於水及低碳醇中之溶解性及分散性優異的有機聚矽氧。提供一種具有聚(N-醯基伸烷基亞胺)鏈段的有機聚矽氧,該聚(N-醯基伸烷基亞胺)鏈段具有由以下通式(1)所表示之重複單元:其中R1代表氫原子或各具有1至22個碳原子之烷基、芳烷基、或芳基,及n為2或3,其中該鏈段係透過含雜原子之伸烷基結合至作為主鏈之有機聚矽氧鏈段之至少兩矽原子之各者,其中該鏈段之數目平均分子量係800至1600,該作為主鏈之有機聚矽氧鏈段與該聚(N-醯基伸烷基亞胺)鏈段之質量比係65/35至82/18,及該作為主鏈之有機聚矽氧鏈段之重量平均分子量係10,000至100,000。
