  Two flavor Nambu-Jona-Lasinio model with N components is studied in curved
space time at finite temperature and density in the leading 1/N expansion. In
four space time dimension the model exhibits first order phase transition for
positive curvature. Whereas in flat space an increase in temperature induces a
second order phase transition even at finite density, in curved space the
transition becomes first order. We obtain the phase boundary in
density-temperature plane and exhibit its behavior with changing curvature. A
three dimensional plot of the phase boundary in $\mu$-T-R space is drawn.
