  Noscale supersymmetry (SUSY) breaking model is investigated in the minimal
extension of the minimal supersymmetric standard model (MSSM) with a gauged
U(1)_{B-L} symmetry. We specifically consider a unification-inspired model with
the gauge groups SU(3)_{C} \times SU(2)_{L} \times U(1)_Y \times U(1)_{B-L}
\subset SU(5) \times U(1)_{5} for illustration. While the noscale boundary
condition at the grand unification scale (M_{G}\simeq 2\times 10^{16} GeV) in
the MSSM is not consistent with phenomenological constraints, we show that it
is if the gaugino of the U(1)_{5} multiplet is several times heavier than the
gauginos of the MSSM. However, if SU(5) \times U(1)_{5} is further embedded in
a larger simple group, e.g. SO(10), the noscale boundary condition at M_{G} is
inconsistent with phenomenological constraints. If we relax the noscale
boundary condition and allow non-zero soft scalar masses for the Higgs fields
which spontaneously break the U(1)_{5} symmetry, the resultant spectrum of SUSY
particles becomes consistent with all the phenomenological constraints, even if
we impose the GUT relation on the gauge coupling and the gaugino mass of the
U(1)_{5}. In this case, the SUSY CP problem is also solved, since the condition
B\mu =0 at the boundary can be imposed consistently with the electroweak
symmetry breaking.
