It is said that the sterilization by pulsed electric field occurs by pores generated by dielectric breakdown of cell membranes. In the paper, we have discussed what factor by the electric field has generated electric discharge on a cell membrane of bacteria and has been dominant for the sterilization ratio. The dominant factor generating the discharge on the cell membrane has been indicated by organizing the relationship between the condition applying the pulse electric field and the sterilization ratio. As the result, it has been shown that the energy consumption in the membrane of bacteria has worked dominantly in sterilization. It shows the possibility that thermal breakdown takes place by the Joule heat generated by the energy that is consumed in the cell membrane. This result is evidence that electrical breakdown is dominant factor for sterilization in PEF.