  We propose a quantization procedure for the nucleon-scalar meson system, in
which an arbitrary mean scalar meson field $\phi$ is introduced. The
equivalence of this procedure with the usual ones is proven for any given value
of $\phi$. By use of this procedure, the scalar meson field in the Walecka's
RMFT and in Chin's RHA are quantized around the mean field. Its corrections on
these theories are considered by perturbation up to the second order. The
arbitrariness of $\phi$ makes us free to fix it at any stage in the
calculation. When we fix it in the way of Walecka's RMFT, the quantum
corrections are big, and the result does not converge. When we fix it in the
way of Chin's RHA, the quantum correction is negligibly small, and the
convergence is excellent. It shows that RHA covers the leading part of quantum
field theory for nuclear systems and is an excellent zeroth order approximation
for further quantum corrections, while the Walecka's RMFT does not. We suggest
to fix the parameter $\phi$ at the end of the whole calculation by minimizing
the total energy per-nucleon for the nuclear matter or the total energy for the
finite nucleus, to make the quantized relativistic mean field theory (QRMFT) a
variational method.
