Irreversible electroporation (IRE) is a new treatment to necrotize abnormal cells by high electric pulses. Electric potential difference over 1 V across the plasma membrane permanently permeabilizes the cell with keeping the extracellular matrix intact if the thermal damage due to the Joule heating effect is avoided. This is the largest advantage of the IRE compared to the other conventional treatment. However, since the IRE has just started to be used in clinical tests, it is important to predict the necrotized region that depends on pulse parameters and electrode arrangement. We therefore examined the numerical solution to the Laplace equation for the static electric field to predict the IRE-induced cell necrosis. Three-dimensionally (3-D) cultured cells in a tissue phantom were experimentally subjected to the electric pulses through a pair of puncture electrodes. The necrotized area was determined as a function of the pulse repetition and compared with the area that was estimated by the numerical analysis.