Focusing a normal pulsed Nd-glass laser radiation on an nupolarized PZT ceramio thin plate, there was no electrical signal was observed between the two surface silver electrodes of the sample before the laser radiation breakdown through the sample. However, as soon as the breakdown of the sample happened, a pulsed electrical signal occured between the two surface-electrodes. The connections of the two electrodes remained unchanged in cases of the laser radiation irradiated the sample from either its front or back surface, the polarities of the produced electrical signals would be opposite to each other. When a hole penetrated on the sample was very small, the polarity of the signal was opposite to incident direction of the radiation. However^ when the hole became big enough, the polarity of the signal would turn to incident direction of the racliafcion.