  Effects of the Dirac sea on the excitation energy of the giant monopole
states are investigated in an analytic way within the $\sigma-\omega$ model.
The excitation energy is determined by the relativistic Landau-Migdal
parameters, $F_0$ and $F_1$. Their analytic expressions are derived in the
relativistic random phase approximation(RRPA) without the Dirac sea, with the
Pauli blocking terms and with the full Dirac sea. It is shown that in the RRPA
based on the mean field approximation the Pauli blocking terms should be
included in the configuration space, according to the relativistic Landau
theory. In the renormalized RRPA, the incompressibility coefficient becomes
negative, if N$\nbar$ excitations are neglected.
