To obtain a solution composition which can form a coating film having hydrophilicity and water resistance on the surface of a substrate by dissolving a polymer having quaternary ammonium salt groups and a tetraalkoxysilane in a solvent.

A polymer (A) having quaternary ammonium groups represented by the formula is blended with a tetraalkoxysilane (B) such as Si(OR5)4. It is desirable that component A is used in an amount of 100 pts.wt., and component B is used in an amount of about 5-1,900 pts.wt. The composition can cure into an organic/inorganic hybrid material, so that it is desirable as a coating material for e.g. the surface of a poorly hydrophilic substrate such as a plastic molding or a metal. In the formula, X is -(CH2)n- (wherein n=2-4); R1 and R2 are each a 1-9C alkyl or hydroxyalkyl; R3 is hydrogen, a 1-9C alkyl, or benzyl; Y is a halogen, R4SO3, or R4OSO3 (wherein R4 is a 1-20C alkyl or phenyl); and R5 is a 6C or lower alkyl.