To obtain a raw material for cosmetics having an affinity for the hair and skin and a smoothness and capable of realizing comfortableness during and after the use, by partially replacing OH groups of a galactomannan molecule with a cationic compound.

In a product of decomposition (preferably enzymatic decomposition for obtaining a uniform mol.wt., wherein β-mannanase derived from microorganisms of the genus Aspergillus or the like is preferred, though the kind and origin of the enzyme are not particularly limited) of a galactomannan (preferably one derived from a vegetable such as locust bean gum and having a mol.wt. of 200,000 to 300,000), OH groups in the galactomannan molecule are partially replaced with a cationic compound (preferably a glycidyltrialkylammonium salt) to obtain a raw material for cosmetics. The decomposition of the galactomannan is preferably limited so that at least 80% of the decomposition product has a mol.wt. of 4,500 to 35,000. The viscosity of 10% aq. soln. of the decomposition product of galactomannan is preferably 5 to 20cPs as determined at 30rpm at 25°C.