[en] The spinless two-band Hubbard model simulating a electron-hole system is investigated on the basis of the dynamical mean-field theory to elucidate the strong correlation effects on the excitonic phase. We calculate the local excitonic susceptibility χ_loc and the renormalization factor Z as functions of the energy level splitting Δ and the Coulomb interaction V between conduction and valence electrons and find that χ_loc is enhanced around the semimetal-to-semiconductor transition where the excitonic phase is expected to be realized. Remarkably, strongly correlated electronic states with Z ∼ 0 are observed for large V in the semimetallic region close to the semimetal-to-semiconductor transition where the both conduction and valence electrons are far away from the half-filling in contrast to the case with the Mott transition. (author)