models considering various types of cells and confluent conditions were constructed. Using ECIS TM, frequency the characteristics of 25 Hz to 60 kHz of impedance of HUVEC (human umbilical vein endothelial cells), BAEC (bovine aortic endothelial cells), in the pre-confluent condition and the full confluent condition of each cell were measured. A mathematical model of the micro-dynamics of the cultured cells measured with ECIS from 1 kHz to 10 kHz, which was the most interesting frequency range for the micro-dynamic analysis in the ECIS methods is proposed. The evaluation method of the cell-to-cell distance (A) and the cell-to-substrate distance (h) could be improved. In the application, we investigated the effect of the X-ray radiation exposure from 1 Gy to 100 Gy on the cultured cells BAEC using the ECIS system. Impedance changes could be confirmed by exposure to 100 Gy. The X-ray stimulation of 100 Gy resulted in a significant increase of the value of the cell-to-cell distance (A).