  Considering that the ultrahigh energy (UHE) upgoing muon neutrino events
around the PeV energy region observed by the IceCube are due to the decay of
super heavy dark matter to neutrinos, we constrain the mass of the decaying
dark matter and its decay lifetime using the IceCube analysis of these
neutrinos in the PeV region. The theoretical fluxes are computed by adpoting
the procedure given in the reference [1,2], where the DGLAP numerical
evolutions of QCD cascades as well as electroweak corrections are included for
evolving the decay process of the super heavy dark matter. Our results indicate
that to explain the IceCube events around PeV region the decaying dark matter
mass $m_\chi$ would be $ \sim 5 \times 10^{7}$ GeV with the decay lifetime
$\tau \sim 7 \times 10^{28}$ sec.
