PURPOSE: To obtain a thin-film organic composite steel plate superior in corrosion resistance by controlling the maximum particle diameter of a fumed silica dispersed in an organic film applied and dried on a plated and chromated steel plate with respect to a thin-film organic composite steel plate used for a motor vehicle and a household electrical appliance.

CONSTITUTION: An organic resin 4 containing 10-40% fumed silica is applied to an upper layer of a steel plate treated with plating 2 and chromating 3 so as to have a dry thickness of 0.5-3.0μm. The fumed silica contained in the dried film has a maximum particle diameter less than the dry thickness of the resin film. A thin-film organic composite steel plate obtained in this manner has few defects in coating and inevitably has few parts possibly turning to corrosion start points, therefore having a superior corrosion resistance.