  We consider a U(1)' gauge symmetry acting on three generations of
right-handed neutrinos. The U(1)' symmetry is broken at the TeV scale and its
remnant discrete symmetry makes one of the right-handed neutrinos stable. As a
natural consequence of the anomaly cancellation, the neutrino mass matrix
consists of a combination of Type I (TeV scale) seesaw and radiative
correction. The stable right-handed neutrino communicates with the Standard
Model via s-channel exchange of the Higgs field and the U(1)' gauge boson, so
that the observed relic density for dark matter is obtained in a wide range of
the parameter space. The experimental signatures in collider and other
experiments are briefly discussed.
