  We propose a new model where the Dirac mass term for neutrinos, the Majorana
mass term for right-handed neutrinos, and the other new fermion masses arise
via the spontaneous breakdown of the $U(1)_{B-L}$ gauge symmetry. The
anomaly-free condition gives four sets of assignment of the B-L charge to new
particles, and three of these sets have an associated global $U(1)_{DM}$
symmetry which stabilizes dark matter candidates. The dark matter candidates
contribute to generating the Dirac mass term for neutrinos at the one-loop
level. Consequently, tiny neutrino masses are generated at the two-loop level
via a Type-I-Seesaw-like mechanism. We show that this model can satisfy current
bounds from neutrino oscillation data, the lepton flavor violation, the relic
abundance of the dark matter, and the direct search for the dark matter. This
model would be tested at future collider experiments and dark matter
experiments.
