  The volume coefficient $K$(=incompressibility of the nuclear matter), the
Coulomb coefficient $K_c$, and the volume-symmetry coefficient $K_{vs}$ of the
nucleus incompressibility are studied in the framework of the relativistic mean
field theory, with aid of the scaling model. It is found that $K= 300\pm 50$MeV
is necessary to account for the empirical values of $K_v$, $K_c$, and $K_{vs}$,
simultaneously. The result is independent on the detail descriptions of the
potential of the $\sigma$-meson self-interaction and is almost independent of
the strength of the $\omega$-meson self-interaction.
