PURPOSE: To obtain a thickening agent composed of a viscous substance obtained by the liquid culture of Laetiporus sulphureus, having excellent feeling to the skin, safety, semi-fluid property and aging stability and suitable as an agent to be compounded to cosmetics, etc.

CONSTITUTION: The thickening agent is composed of a viscous substance obtained by culturing Laetiporus sulphurus (a fungus of the family Polyporaceae) in a liquid medium containing e.g. a carbon source such as glucose, a nitrogen source such as peptone and inorganic salts, natural nutrient sources, vitamins, amino acids, etc., under aerobic condition.