Abstract: Bipolar junction transistors may be burned out by injected electromagnetic pulse. The effects of electromagnetic pulse injected from base on bipolar junction transistor were studied with 2-dimensional simulation. Results show that the hot spot locates on the edge of base electrode due to the distribution of current density and electric field. The energy needed for burnout is the smallest when pulses are injected from base among the three electrodes for the heat generation is centralized at that point. If the pulse width is short, the energy needed for burnout nearly remains constant while the pulse power needed is approximately in inverse proportion to the pulse width.