Abstract: A method of curing a photo-curable coating composition comprises multi-stage irradiation steps with actinic radiations in the presence of air: the initial step involving irradiation with actinic radiation having wavelengths in a range from about 185 to 500 millimicrons with dominant wavelength or wavelengths between about 380 and 420 millimicrons and the subsequent step involving irradiation with another actinic radiation of wavelengths within the same range as those of the radiation used for the initial step but having dominant wavelength or wavelengths within a range shorter than those of the radiation used therefor and the initial irradiation being effected so as to cure the lower part of the coating layer with the surface portion thereof left uncured and the subsequent irradiation leading to the full cure of the surface portion thereof.