  Curvature induced phase transition is thoroughly investigated in a four-
fermion theory with $N$ components of fermions for arbitrary space-time
dimensions $(2 \leq D < 4)$. We adopt the $1/N$ expansion method and calculate
the effective potential for a composite operator $\bar{\psi}\psi$. The
resulting effective potential is expanded asymptotically in terms of the
space-time curvature $R$ by using the Riemann normal coordinate. We assume that
the space-time curves slowly and keep only terms independent of $R$ and terms
linear in $R$. Evaluating the effective potential it is found that the
first-order phase transition is caused and the broken chiral symmetry is
restored for a large positive curvature. In the space-time with a negative
curvature the chiral symmetry is broken down even if the coupling constant of
the four-fermion interaction is sufficiently small. We present the behavior of
the dynamically generated fermion mass. The critical curvature, $R_{cr}$, which
divides the symmetric and asymmetric phases is obtained analytically as a
function of the space-time dimension $D$. At the four-dimensional limit our
result $R_{cr}$ agrees with the exact results known in de Sitter space and
Einstein universe.
