A vinyl polymer having, at a molecular chain terminus, a structure represented
by the general formula 1:
##STR1##
(wherein R3 is a hydroxy, amino, epoxy, carboxylic acid, ester,
ether, amide or silyl group, an alkenyl group having low polymerizability, an organic
compound having 1 to 20 carbon atoms, X is a halogen atom, a nitroxide or sulfide
group or a cobalt porphyrin complex).
