  We propose a Minimal E_6 Supersymmetric Standard Model (ME$_6$SSM) which
allows Planck scale unification, provides a solution to the $\mu$ problem and
predicts a new Z'. Above the conventional GUT scale $M_{GUT}\sim 10^{16}$ GeV
the gauge group corresponds to a left-right symmetric Supersymmetric Pati-Salam
model, together with an additional $U(1)_{\psi}$ gauge group arising from an
E_6 gauge group broken near the Planck scale. Below $M_{GUT}$ the ME$_6$SSM
contains three reducible $\mathbf{27}$ representations of the Standard Model
gauge group together with an additional U(1)_X gauge group, consisting of a
novel and non-trivial linear combination of $U(1)_{\psi}$ and two Pati-Salam
generators, which is broken at the TeV scale by the same singlet which also
generates the effective $\mu$ term, resulting in a new low energy Z' gauge
boson. We discuss the phenomenology of the new Z' gauge boson in some detail.
