Provided are: a cellulose ether containing a cationic group, which can impart an excellent slipperiness and an excellent long- lasting feeling of the slipperiness during rinsing, excellent smoothness hair upon finger -combing, excellent softness and an excellent coated feeling to hair when added to a hair cleansing agent, and can impart an excellent moisturized feeling after drying to skin when added to a skin cleansing agent and a surfactant composition , a hair cleansing agent composition , a skin cleansing agent composition, a hair conditioning agent composition and a hair treating agent composition , each of which contains the cellulose ether. [1] A cellulose ether containing a cationic group , which has a main chain derived from anhydroglucose , wherein the degree of substitution of a cationized oxyalkylene group is 0.01 to 1.0 inclusive, the degree of substitution of a glycerol group is 0.5 to 5.0 inclusive and the degree of substitution of a group having a specific structure containing a C3-7 hydrocarbon group is 0.0001 to 0.2 inclusive per the anhydroglucose unit [2] a surfactant composition comprising the cellulose ether containing a cationic group , a surfactant and water [3] a hair cleansing agent composition and a skin cleansing agent composition , each comprising the cellulose ether containing a cationic group a surfactant and water [4] a hair conditioning agent composition comprising the cellulose ether containing a cationic group , a surfactant , an oily agent and water and [5] a hair treating agent composition comprising the cellulose ether containing a cationic group and at least one treating agent selected from a dye for hair dyeing use , an oxidizing agent, an alkali agent and a keratin -reducing agent.