PURPOSE: To obtain a coating compsn. for precoated steel sheet which forms a coating film with an excellent processibility and a high hardness by adding an organosilica sol to a coating compsn. contg. a high-molecular polyester resin and a melamine resin as the main components.

CONSTITUTION: This compsn. contains a polyester resin having a hydroxyl value of, pref., 2-100 and a number-average mol.wt. of 3,000-50.000, a melamine resin pref. alkyl-etherified, and an organosilica sol in an amt. of 1-40wt.% (solid- basis) of the sum of the polyester and epoxy resins. An organosilica sol dispersed in a xylene-methanol mixture, methyl ethyl ketone, or methyl isobutyl ketone is esp. pref.