  We investigate the relic abundance of dark matter in the minimal universal
extra dimension model including resonance processes by second Kaluza-Klein (KK)
particles in all coannihilation processes. After including second KK resonance
processes, the relic abundance of dark matter is reduced by about 30%. Thus,
the compactification scale 1/R of the extra dimension consistent with the WMAP
observation is increased by a few hundred GeV. As a result, the cosmologically
allowed compactification scale is 600 GeV < 1/R < 1400 GeV for Lambda R = 20.
