PURPOSE: To improve the adhesiveness of a cured polymer to a metal support and to impart further effect as a photoinitiator not using ether by providing a xanthogenate or a dithiocarbamate group to at least one terminal of a polymer chain.

CONSTITUTION: Transition metal xanthogenate, dithiocarbamate and dithiophosphate are used together with an initiator selected from organohalogen and tertiary amine compds. to provide an irradiation activating initiation mechanism of a radical-polymerizable ethylenically unsaturated compd., for example, a (meth)acrylic ester.