Abstract: A rust preventive coating composition to be applied to the underfloor of an automotive vehicle for the purpose of preventing the underfloor from being rusted. The rust preventive coating composition comprises asphalt, metallic salt of petroleum sulfonic acid, metallic salt of petrolatum oxide, wax-like material, microwax, metallic salt of lanolin fatty acid, metallic salt of synthetic sulfonic acid, plasticizer, solvent, extender pigment, additive, reforming agent and inorganic running preventive agent. The extender pigment includes barium sulfate ranging not less than 20 wt % of the total amount of the extender pigment, and calcium carbonate ranging not less than 5 wt % of the total amount of the extender pigment. The reforming agent ranges from 1 to 10 wt % of the total amount of the rust preventive coating coposition. The inorganic running preventive agnet ranges from 0.5 to 10 wt % of the total amount of the rust preventive coating composition.