To provide a hair treatment composition capable of imparting improved voluminousness, improved gloss and humidity, and excellent combability in a dried state to the hair and capable of restoring damaged hair.

This hair treatment composition is prepared by mixing (A) at least one. kind of fatty acids having 10-24 carbon atoms, (B) at least one kind of compounds expressed by the formula [wherein R1 and R2 are each a (hydroxy-substituted) (8-22C) alkyl or alkenyl; R3 and R4 are each a 1-3C alkyl or a group expressed by the formula CH2-CH2-O-[E0]zH; (x), (y) and (z) are each 0-5; Y- is an anion] and (C) an aqueous carrier as a base.