  We reevaluate the thermal relic density of the Kaluza-Klein (KK) dark matter
in universal extra dimension models. In particular, we consider the effect of
the resonance caused by second KK particles on the density. We find that the
annihilation cross sections relevant to the density are significantly enhanced
due to the resonance when the Higgs boson mass is large enough (m_h \gtrsim 200
GeV). As a result, the mass of the dark matter particle consistent with the
WMAP observation is increased compared to the result which does not include any
resonance.
