  A new high precision measurement of the $J/\psi$- and $\psi'$-meson masses
has been performed at the VEPP-4M collider using the KEDR detector. The
resonant depolarization method has been employed for the absolute calibration
of the beam energy. The following mass values have been obtained:
  $M_{J/\psi} = 3096.917 \pm 0.010 \pm 0.007$ MeV,
  $M_{\psi'} = 3686.111 \pm 0.025 \pm 0.009$ MeV.
  The relative measurement accuracy has reached $4. 10^{-6}$ for $J/\psi$ and
$7. 10^{-6}$ for $\psi'$, approximately 3 times better than in the previous
precise experiments.
