  We investigate how the neutron drip line is related to the density dependence
of the symmetry energy, by using a macroscopic nuclear model that allows us to
calculate nuclear masses in a way dependent on the equation of state of
asymmetric nuclear matter. The neutron drip line obtained from these masses is
shown to appreciably shift to a neutron-rich side in a nuclear chart as the
density derivative of the symmetry energy increases. Such shift is clearly seen
for light nuclei, a feature coming mainly from the surface property of
neutron-rich nuclei.
