PURPOSE: To provide a hair liquid base material exhibiting excellent water solubility and transparency without being affected by the addition of an anionic or cationic substance, capable of giving a good luster to hair and simultaneously satisfying the properties even under highly wet conditions.

CONSTITUTION: A hair liquid base material comprises an amphoteric product produced by hydrolyzing a copolymer comprising (A) 15-60wt.%, preferably 20-40wt.%, of an acrylamide monomer of formula I (R1 is methyl, H; R2 is 1-12C alkyl) and (B) 40-70wt.%, preferably 50-65wt.%, of an amine monomer of formula II (R3 is 1-6C alkylene; R4 is 1-3C alkyl; X is halogen; Y is O, NH). The agent is soluble in water and hydrophilic organic solvents, has good compatibility with natural gases used as propellants, can be readily removed before the hair is washed, does not deteriorate the luster of the hair even under the conditions of high temperature and high moisture, has an excellent blocking- resistant property, and is not solidified with anionic or cationic substances.