Neutron scattering measurements have played important roles in not only the structural information study, but also the dynamical insight of solid state ionic materials in the form of polymer, crystalline and glassy materials. Quasielastic neutron scattering (QENS) measurement explores the diffusion mechanism of mobile ions, on the other hand, inelastic neutron scattering (INS) reveals the dynamical insight of solid ionic conductor materials. Here we present the neutron scattering study of superionic glass (LiI)0.3(LiPO3)0.7 by using the inelastic neutron spectrometer AMATERAS at the Japan Proton Accelerator Research Complex (J-PARC). Simultaneous two dimensional maps of dynamical structure factor S(Q,E) with the incident energy Ei 93.85, 23.59, 10.57 and 5.92meV over a wide momentum transfer (Q)-range were observed for (LiI)0.3(LiPO3)0.7. The first sharp diffraction peak appears at Q ~1.8Å−1 in the elastic structure factor. From the inelastic scattering, low energy excitation or the Boson Peak appears at ~6.0–7.0meV. The extra quasielastic scattering was observed in the energy range 1meV<E<3meV at 285K but not at 20K. The Q dependence of the dynamical structure factor S(Q,E) can be approximated to the long-wave acoustic like density fluctuation.