  We study the dynamical symmetry breaking in the gauge-Higgs unification of
the 5D theory compactified on an orbifold, $S^1/Z_2$. This theory identifies
Wilson line degrees of freedoms as ``Higgs doublets''. We consider $SU(3)_c
\times SU(3)_W$ and SU(6) models with the compactification scale of order a few
TeV. The gauge symmetries are reduced to $SU(3)_c \times SU(2)_L \times U(1)_Y$
and $SU(3)_c \times SU(2)_L \times U(1)_Y \times U(1)$, respectively, through
the orbifolding boundary conditions. We estimate the one loop effective
potential of ``Higgs doublets'', and find that the electro-weak breaking is
realized through the radiative corrections when there are suitable numbers of
bulk fields possessing the suitable representations. The masses of ``Higgs
doublets'' are ${\mathcal O}(100)$ GeV in this scenario.
