  The parameters in the pseudoscalar meson mass formula in quenched chiral
perturbation theory to one-loop order are determined by quenched lattice QCD
with overlap Dirac operator, and from which the light quark masses are
determined with the experimental inputs of pion and kaon masses, and the pion
decay constant. Our results are $ m_{u,d} = 5.3 \pm 0.3 $ MeV, and $ m_s =
115\pm 8 $ MeV, in the $ \bar{MS} $ scheme at scale $ \mu = 2 $ GeV.
