  A new relativistic Hartree-Fock approach with density-dependent $\sigma$,
$\omega$, $\rho$ and $\pi$ meson-nucleon couplings for finite nuclei and
nuclear matter is presented. Good description for finite nuclei and nuclear
matter is achieved with a number of adjustable parameters comparable to that of
the relativistic mean field approach. With the Fock terms, the contribution of
the $\pi$-meson is included and the description for the nucleon effective mass
and its isospin and energy dependence is improved.
