  We discuss an extension of the minimal Higgs triplet model with a classically
conformal invariance and with a gauged $U(1)_{B-L}$ symmetry. In our scenario,
tiny masses of neutrinos are generated by a hybrid contribution from the type-I
and type-II seesaw mechanisms. The shape of the Higgs potential at low energies
is determined by solving one-loop renormalization group equations for all the
scalar quartic couplings with a set of initial values of parameters at the
Planck scale. We find a successful set of the parameters in which the
$U(1)_{B-L}$ symmetry is radiatively broken via the Coleman-Weinberg mechanism
at the ${\cal O}$(10) TeV scale, and the electroweak symmetry breaking is also
triggered by the $U(1)_{B-L}$ breaking. Under this configuration, we can
predict various low energy observables such as the mass spectrum of extra Higgs
bosons, and the mixing angles. Furthermore, using these predicted mass
parameters, we obtain upper limits on Yukawa couplings among an isospin triplet
Higgs field and lepton doublets from lepton flavor violation data.
