  A simple model of the Majorana neutrino with the see-saw mechanism is
studied, assuming that two light neutrinos are the hot dark matters with equal
mass of 2.4 eV in the cold plus hot dark matter model of cosmology. We find
that the heavy neutrino, which is the see-saw partner with the remaining one
light neutrino, can be the cold dark matter, if the light neutrino is exactly
massless. This cold dark matter neutrino is allowed to have the mass of the
wide range from 5.9 x 10^2 eV to 2.2 x 10^7 eV.
