  The observed hierarchical charged fermion masses of three generations seem to
imply that these masses are originally universal for three generations and then
get exponential suppression with "quantized exponents" by some mechanism. We
argue that such remarkable feature of hierarchical fermion mass spectrum may be
naturally understood in the scenario of gauge-Higgs unification, where the
universality of fermion masses is guaranteed by the fact that Higgs boson is
originally gauge boson in this scenario and also the quantized exponents may be
attributed to the well-known quantization condition of magnetic charge of the
magnetic monopole placed inside the torus, as the extra dimensional space.
Because of the presence of the magnetic monopole, we get a chiral theory and
multiple Kaluza-Klein zero modes even if we introduce only a single
6-dimensional Weyl fermion. We present two types of three generation model,
which succeed to realize the remarkable hierarchical mass spectrum.
