oint that a coating filmformed from the obtained curable composition is excellent in solvent resistance.In the formula (I), R.sup.1 is hydrogen atom or an alkyl group having 1 to 10 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms, such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group ort-butyl group.