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 Kähler potential the L−Hᵤ 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−σ constraint from the WMAP7−BAO−H₀ data sets its lower bound M⌄(R) ≳ 1 TeV. Generation of the baryon asymmetry is naturally implemented in this model. We expect that within a few years new observational data from the Planck satellite will clearly discriminate this model from other existing inflationary models arising from the same Lagrangian, and possibly yield stringent constraints on M⌄(R).