A photocurable composition comprising an ultraviolet radical polymerization initiator, a cationic dye with absorptions in the visible light region, a quaternary boron salt and optionally a polymerization accelerator, is irradiated with ultraviolet light and visible light either simultaneously or separately, to achieve adequate hardening in air of both the surface and the interior of the cured product, and to provide a cured product with an excellent appearance and without production of coloring substances derived from the polymerization initiator.