The attenuated total reflection spectroscopy system with the Si container attached on the prism has been demonstrated as an efficient technique to obtain the dielectric properties of living cells in the THz range. We proposed a method to determine the dielectric responses of living cells based on the combination of the single-interface and two-interface ATR models without cell thickness. The experimental results for living glial-like cells (PC12, SVG P12 and HMO6) showed the dielectric responses in the THz region were related significantly to cell number, intracellular fluid, and cell structure. Moreover, the glioma cells (C6 and U87) exhibited different dielectric properties compared with the glial-like cells, which could be one reason for the glioma tissue diagnosis using THz wave.