The inertness of eight-coordinate tetrakis(picolinato)tungsten(IV) complex has been investigated by spectroscopic method in nonpolar solvent at 60$^{circ}C$, 75$^{circ}C$, 90$^{circ}C$, 120$^{circ}C$, and reflux condition. Until 2 days, showed the inertness whether existance of oxygen or not. After 2 days, showed the oxidation of W(IV) complex much more rapidly than substitution, which had $k_{obs}(sec^{-1}) {varpropto} 1/[ligand]^2$. On sealing the sample under Ar gas, showed the inertness until 50 days, which had $k_{obs}(sec^{-1}) = 8.8{ imes} 10^{-7}$. The$^1H$-NMR peak of $H_6$ in complex was diminished, otherwise that of free ligand was grown up. This result indicated that this complex was very inert.