  We study flat directions and soft scalar masses using a $Z_3$ orbifold model
with $SU(3) \times SU(2) \times U(1)$ gauge group and extra gauge symmetries
including an anomalous $U(1)$ symmetry. Soft scalar masses contain $D$-term
contributions and particle mixing effects after symmetry breaking and they are
parametrized by a few number of parameters. Some specific relations among
scalar masses are obtained.
