  The density-dependent finite-range Gogny force has been used to derive the
effective Hamiltonian for the shell-model calculations of nuclei. The density
dependence simulates an equivalent three-body force, while the finite range
gives a Gaussian distribution of the interaction in the momentum space and
hence leads to an automatic smooth decoupling between low-momentum and
high-momentum components of the interaction, which is important for
finite-space shell-model calculations. Two-body interaction matrix elements,
single-particle energies and the core energy of the shell model can be
determined by the unified Gogny force. The analytical form of the Gogny force
is advantageous to treat cross-shell cases, while it is difficult to determine
the cross-shell matrix elements and single-particle energies using an empirical
Hamiltonian by fitting experimental data with a large number of matrix
elements. In this paper, we have applied the Gogny-force effective shell-model
Hamiltonian to the ${\it p}$- and ${\it sd}$-shell nuclei. The results show
good agreements with experimental data and other calculations using empirical
Hamiltonians. The experimentally-known neutron drip line of oxygen isotopes and
the ground states of typical nuclei $^{10}$B and $^{18}$N can be reproduced, in
which the role of three-body force is non-negligible. The Gogny-force derived
effective Hamiltonian has also been applied to the cross-shell calculations of
the ${\it sd}$-${\it pf}$ shell.
