PURPOSE: To obtain a hydrophilic polymer excellent in adsorption on the solid surface of a hair, a skin, a fiber, etc., in an aqueous medium and removal from the solid surface during cleaning and also having advantageous points of an organopolysiloxane and to provide its production method, a cosmetic containing it and a fiber-treating agent containing it.

CONSTITUTION: The characteristics of this polycondensate comprise the main chain containing ester bonds and/or amide bonds, the weightaverage molecular weight within a range of 3×103 to 3×106, the side chains including both organopolysiloxane groups and hydrophilic groups and its water-soluble property of the whole polymer. This polycondensate is used as a film-forming material to provide a cosmetic and a fiber-treating agent.