There is provided a composition for forming anti-reflective coating for use in a lithography process with irradiation light from F2 excimer laser (wavelength 157 nm) which has a high effect of inhibiting reflected light and causes no intermixing with resist layers, and an anti-reflective coating prepared from the composition, and a method of controlling attenuation coefficient of the anti-reflective coating.Concretely, the composition is one containing a polymer compound containing halogen atom for forming anti-reflective coating for use in a lithographic process in manufacture of a semiconductor device. The polymer compound is one which halogen atom is introduced to a main chain thereof and/or a side chain bonded to the main chain. The attenuation coefficient can be controlled by changing the content of halogen atom in the solid content of the composition.