Poly(n-hexyl isocyanate) was synthesized by anionic polymerization using various oxy-initiators, including sodium phenoxide (Na-PO), sodium benzhydroxide (Na-BH), and sodium methoxyphenylethoidde (Na-MPE). We optimized polymerization conditions. To confirm the living natures of the polymerization, we carried out various polymerizations changing mole ratio between monomers and initiators and a postpolymerization by sequential monomer addition method. Our results indicated that the anionic polymerization of n-hexyl isocyanate was not controlled using Na-PO and Na-MPE. However, Na-BH as an initiator is favorable for the living anionic polymerization of n-hexyl isocyanate because it has a dual function in the initiation and in the efficient prevetion of trimerization by reducing the reactivity at the growth chain ends. Polymers were thus synthesized with predictable molecular weights (MW), narrow molecular weight distributions (MIND), and high yields.