  Gauge-Higgs unification is the fascinating scenario solving the hierarchy
problem without supersymmetry. In this scenario, the Standard Model (SM) Higgs
doublet is identified with extra component of the gauge field in higher
dimensions and its mass becomes finite and stable under quantum corrections due
to the higher dimensional gauge symmetry. On the other hand, Yukawa coupling is
provided by the gauge coupling, which seems to mean that the flavor mixing and
CP violation do not arise at it stands. In this talk, we discuss that the
flavor mixing is originated from simultaneously non-diagonalizable bulk and
brane mass matrices. Then, this mechanism is applied to various flavor changing
neutral current (FCNC) processes via Kaluza-Klein (KK) gauge boson exchange at
tree level and constraints for compactification scale are obtained.
