Biological effects of intense pulsed electric fields (PEF) have been intensively investigated in the last decade. PEFs are c apable of giving biological targets unique stress dependent on its pulse duration, rise time and field strength. In general, nanosecond pulsed electric fields (nsPEF) cause intracellular effects, while micro-to-millisecond long pulses affect the cell membrane. We are using an intense burst sinusoidal electric field (IBSEF) instead of rectangular pulses that have wide frequency band. The use of IBSEFs, which have narrow frequency band, allows to give well-defined electric fields to biological targets, helping us discuss the biological effect in the frequency domain. In the previous work, we have experiment ally demonstrated that the application of non-thermal 100 kV /m IBSEFs induce the breakage of DNAs in Chinese hamster ovary cells, and the breakage depends on the frequency and the strength of the field.