  We propose a radiative seesaw model with an inert triplet scalar field in
which Majorana neutrino masses are generated at the two loop level. There are
fermionic or bosonic dark matter candidates in the model. We find that each
candidate can satisfy the WMAP data when its mass is taken to be around the
half of the mass of the standard model like Higgs boson. We also discuss
phenomenology of the inert triplet scalar bosons, especially focusing on the
doubly-charged scalar bosons at Large Hadron Collider in parameter regions
constrained by the electroweak precision data and WMAP data. We study how we
can distinguish our model from the minimal Higgs triplet model.
