[en] In this study, NaI transparent ceramics were synthesized by the spark plasma sintering method, also optical and scintillation properties were investigated. To evaluate the potential of the transparent ceramics, a NaI single crystal was also prepared by the vertical Bridgman-Stockbarger method. The diffuse transmittance of the transparent ceramic fabricated at 470 ℃ was equivalent to that of the single crystal. All the samples showed scintillation peaking at 320 nm due to self-trapped exciton. In addition, scintillation peaks ascribed from lattice defects were detected at 450 nm for the transparent ceramics and 540 nm for the single crystal. The scintillation decay time constants of the transparent ceramic fabricated at 440 ℃ were 5.7, 18, and 189 ns. The light yield of the transparent ceramic turned out to be 910 photons MeV⁻¹ and was two-thirds of the single crystal. (author)