To obtain a polymer composition capable of forming an exceedingly water-repellent surface from which adherent water drops can easily slip by including a hydrolyzable-alkoxysilyl-containing siloxane polymer obtained by the copolymerization of a siloxane macromonomer having a specified structure with a hydrolyzable-alkoxysilyl-containing monomer and other copolymerizable unsaturated monomers.

This composition is one containing a hydrolyzable-alkoxysilyl- containing siloxane polymer having a number-average molecular weight of 1,000-100,000 and obtained by copolymerizing 1-40 wt.% siloxane macromonomer represented by formula I or II with 5-50 wt.% hydrolyzable-alkoxysilyl-containing monomer such as vinyltrimethoxysilane and 10-94 wt.% other copolymerizable unsaturated monomers such as (meth)acrylic acid. The composition may additionally contain a crosslinking agent such as an amino resin, a curing catalyst, a solvent, etc. In the formulae, R1 is a 1-10C alkyl; R2, R5 and R6 are each a divalent 1-10C hydrocarbon group; R3, R4 and R7 are each hydrogen or methyl; and m and n are each 6-300.