NEW MATERIAL:A compound shown by formula I (n is 8W16 integer) and a salt thereof.

EXAMPLE: N-Lauroyl-N-(3-hydroxypropyl)glycine.

USE: A surface active agent preferably usable for heir and skin detergent for little children, kitchen detergent for housewives having the hands to be readily chapped, daily shampoo, shampoo for beauty culture having low irritation, etc., because of improved hard water resistance, low irritation and improved surface active performance.

PREPARATION: A compound shown by formula II is reacted with a compound shown by formula III in the presence of a base to give a compound shown by formula I. The compound keeps effects as surface active agent when it is used not only for city water but also underground water, hot spring, seawater, etc., and use of the compound as an additive for other surface active agents provides hard water with foam increasing effects. Further it is usable as a detergent for metallic surface, antistatic agent, fiber treatment, penetrating agent, emulsifying agent for emulsion polymerization, etc., similarly as an ordinary surface active agent.