A known signal with random noise was analyzed by the theory of natural observation method, the just new technique of waveform analysis which noticed instantaneous characteristics of a signal. And, as the important characteristic of natural observation method, it is mentioned that this method is a real-time analysis. It was shown that the minute fluctuation signal in noise could detect clearly by natural observation transform. As an application example, an atmospheric electricity variation signal was analyzed by natural observation transform to clarify atmospheric electricity minute fluctuation signal with seismic wave propagation. As a result, it was shown that applying the natural observation method to observation signals of electromagnetic phenomenon with the earthquake was very useful.