A thickener which is superior in handling characteristics and blending stability and has a high thickening action is provided, comprising a fatty acid alkanolamide represented by the general formula (1) and a surfactant composition comprising the thickener and at least one surfactant:
wherein R 1 represents a straight-chain or branched alkyl or alkenyl group having 5 to 21 carbon atoms which may be substituted with at least one hydroxy group, R 2 and R 3 independently represent an alkyl group having 1 to 2 carbon atoms, AO represents an oxyalkylene group having 2 to 4 carbon atoms and n denotes a number of 0 to 10 in average.