1-(carboxyalkyl) trimethyl ammonium chlorides such as 1-(carboxyundecyl) trimethyl ammonium chloride and 1-(carboxytridecyl) trimethyiammonium chloride were synthesized by the reaction of ${alpha}-bromoalkanoic$ acid with trimethyl amine hydrochloride. In other hand, (carboxymethyl) alkyl dimethyl ammonium chlorides such as (carboxymethyl) dodecyl dimethyl ammonium chloride and (carboxymethyl) tetradecyl dimethyl ammonium chloride were synthesized by the reaction of alkyl dimethylamine with sodium chloroacetate. The four kinds of alky carboxy betaine such as 2-(trimethylammonio) dodecanoate, 2-(trimethyl ammonio) tetradecanoate, (dodecyl dimethylammonio) ethanoate and (tetradecyl dimethyl ammonio) ethanoate were prepared from 1-(carboxyalkyl) trimethyl ammonium chlorides or (carboxymethy1) alkyl dimethyl ammonium chlorides. The surface activities including surface tension, emulsifying power, foaming power, foam stability, deflocculating effect, effectiveness of wettability and solubilizing effect were measured and also critical micelle concentration and hydrophilic-lipophilic. balance(HLB) were evaluated. These carboxy betaines show good surface activities as O/W type emulsifing agent and detergent.