  We propose a new mechanism which simultaneously explains tiny neutrino
masses, stability of dark matter and baryon asymmetry of the Universe via
leptogenesis due to the common origin: a spontaneous breaking of a $U(1)_X$
gauge symmetry at TeV scale. The $U(1)_X$ breaking provides small Majorana
masses of vector-like leptons which generate small mass differences among them,
and enhance their CP-violating decays via the resonant effect. Such
CP-violation and lepton number violation turns out to be a sufficient amount of
the observed baryon asymmetry through leptogenesis. The Majorana masses from
the $U(1)_X$ breaking also induce radiative generation of masses for active
neutrinos at one-loop level. Furthermore, a $Z_2$ symmetry appears as a remnant
of the $U(1)_X$ breaking, which guarantees the stability of dark matter. We
construct a simple renormalizable model to realize the above mechanism, and
show a benchmark point which can explain observed neutrino oscillations, dark
matter data and the baryon asymmetry at the same time.
