PURPOSE: To obtain a hair tonic having excellent moisture retaining effects and hair producing effects by extracting mainly a stringing substance in natural yams.

CONSTITUTION: Natural yams are made into a semidry state in the sun, cut into pieces of proper size, washed, steamed at about 80°C for proper time, naturally cooled, then put in a box equipped with a venting hole, stored and fermented in a chamber and heated or sterilized with an ethylene oxide gas. The prepared powder is mixed with water through an emulsifying agent, emulsified and filtered to give filtrate. The filtrate is mixed with 10-50% water- immiscible solvent while stirring, allowed to stand for about 24 hours in a dark place, a separated water layer part is collected, the water layer part is blended with 30-90% water-miscible solvent while stirring and allowed to stand for about 24 hours in a dark place. The formed precipitate layer part is taken out, the solvent and water are removed under reduced pressure to give an extract consisting essentially of saccharide and protein of natural yam.