Abstract: The present invention intends to provide a thermosetting coating composition provided with workability, excellent adhesion, weatherability, good appearance, etc. capable of use in a primerless colored base coat and top clear coat by a 2-coat, 1-bake method on a polyolefinic substrate. Moreover, the present invention intends to provide a coated body having excellent adhesion, weatherability, good appearance, etc. realized by a 2-coat, 1-bake method. This thermosetting coating composition is a composition comprising a graft copolymer obtained by copolymerizing acrylic monomer, unsaturated carboxylic acids, acrylic monomers containing hydroxyl group with chlorinated polyolefin containing anhydride in the presence of organic solvents. This coating composition is available for use as a primerless colored base coat 2-coat, 1-bake coating on the polyolefinic substrates.