  We investigate a 5D SU(6) grand gauge-Higgs unification model compactified on
an orbifold S^1/Z_2. Ordinary quarks and leptons, together with right-handed
neutrinos, are just accommodated into a minimal set of representations of the
gauge group, without introducing any exotic states. The proton decay turns out
to be forbidden at least at the tree level. We also find a correct electroweak
symmetry breaking SU(2)_L \times U(1)_Y \to U(1)_{em} is easily realized by
introducing suitable number of adjoint fermions.
