  We apply Koide's mass relation of charged leptons to neutrinos and quarks,
with both the normal and inverted mass schemes of neutrinos discussed. We
introduce the parameters $k_{\nu}$, $k_u$ and $k_d$ to describe the deviations
of neutrinos and quarks from Koide's relation, and suggest a quark-lepton
complementarity of masses such as $ k_{l}+k_{d} \approx k_{\nu}+k_{u} \approx
2$. The masses of neutrinos are determined from the improved relation, and they
are strongly hierarchical (with the different orders of magnitude of $10^{-5}
eV$, $10^{-3} eV$, and $10^{-2} eV$).
