  In the $SO(5) \times U(1)$ gauge-Higgs unification the lightest, neutral
component of $n_F$ $SO(5)$-spinor fermions (dark fermions), which are relevant
for having the observed unstable Higgs boson, becomes the dark matter of the
universe. We show that the relic abundance of the dark matter determined by
WMAP and Planck data is reproduced, below the bound placed by the direct
detection experiment by LUX, by a model with one light and three heavier
($n_F=4$) dark fermions with the lightest one of a mass from 2.3$\,$TeV to
3.1$\,$TeV. The corresponding Aharonov-Bohm phase $\theta_H$ in the fifth
dimension ranges from 0.097 to 0.074. The case of $n_F=3$ ($n_F = 5, 6$) dark
fermions yields the relic abundance smaller (larger) than the observed limit.
