Provided is a novel surfactant which is less irritating to the skin or the mucous membrane than prior art surfactants, which exhibits excellent conditioning effects and fabric softening effects, and which can be widely used in a toiletry or detergent composition. Basic amino-acid derivatives or salts thereof obtained by reacting glycidyl ethers with basic amino acids or salts thereof are incorporated into a toiletry or detergent composition or a conditioning agent.