  We propose a cosmological inflationary scenario based on the
supergravity-embedded Standard Model supplemented by the right-handed
neutrinos. We show that with an appropriate Kahler potential the L-H_u
direction gives rise to successful inflation that is similar to the recently
proposed gravitationally coupled Higgs inflation model but is free from the
unitarity problem. The mass scale $M_R$ of the right-handed neutrinos is
subject to the seesaw relation and the present 2-$\sigma$ constraint from the
WMAP7-BAO-H_0 data sets its lower bound $M_R\gtrsim$ 1 TeV. Generation of the
baryon asymmetry is naturally implemented in this model. We expect within a few
years new observational data from the Planck satellite clearly discriminates
this model from other existing inflationary models arising from the same
Lagrangian, and possibly yields stringent constraints on $M_R$.
