  The existence of the inflationary era in the early Universe seems to be
strongly supported by recent CMB observations. However, only a few realistic
inflation scenarios which have close relation to particle physics seem to have
been known unfortunately. The radiative neutrino mass model with inert doublet
dark matter is a promising model for the present experimental issues which
cannot be explained within the standard model. In order to make the model
include inflation, we extend it by a complex scalar field with a specific
potential. This scalar could be closely related to the neutrino mass generation
at a TeV scale as well as inflation. We show that the inflation favored by the
CMB observations could be realized even if inflaton takes sub-Planck values
during inflation.
