To obtain a non-silica or non-water-glass type highly hydrophilic coating material which gives a coating film being excellent in hydrophilicity and anticorrosiveness and being relatively soft and therefore nonabrasive to a mold in drilling by copolymerizing a hydrophilic monomer with a polyfunctional ethylenically unsaturated monomer in the presence of an alumina sol having a specified particle diameter.

At least one hydrophilic monomer (b) of formula I (wherein R1 is H or methyl; R2 is H or R3-O-R4; R3 is a 1-4C alkylene; R4 is H or a 1-4C alkyl) or formula II (wherein R5 and R6 are each H or methyl; R7 is H or a 1-4C alkyl; and n is 1-50) is copolymerized with a polyfunctional ethylenically unsaturated monomer (C) in the presence of an alumina sol (a) having a particle diameter of 0.02-2μm. Alternatively, at least one component (b) and component (c) are copolymerized with other ethylenically unsaturated monomers (d) copolymerizable therewith in the presence of the alumina sol. In this way, a highly hydrophilic coating material containing organic/inorganic composite particles containing an alumina sol chiefly on their surfaces and a water-soluble resin is obtained.