Objective : Assuming that the characteristic of meridian system has been similar to this of electric potentials in human body and that measurements of electric potential at well(井穴) and sea(合穴) points in branches of the twelve meridians will be representative of measurements of the twelve meridians, to measure the electric potentials in twenty aged and fifty aged healthy volunteers groups at sleeping(SG) and awakening(AG), and then to find out the characteristic of meridian system among 2 groups. Methods : We selected who thirty healthy volunteers were diagnosed by a blood test, urine examination and differentiation of syndromes by five viscera(五臟辨證) among volunteers. Their electric potential of well and sea points in the meridians were simultaneously measured by physiograph. Results : Measurements were analyzed by statistical factor analysis, we obtained that the both left and right side electric potential of well and sea points in branches of the twelves meridians were unclearly divided into four factors according to age and whether sleeping or not, which were the three Yin meridians of the hand, the three Yang channels of the hand, the three Yin meridians of the foot, and the three Yin meridians of the foot. Conclusion : In conclusion, using the sequently measuring method, we obtained that electrical potentials of well and sea points in branches of the twelves meridians were divided into two factors, but the simultaneously measuring method, those were divided into four factors. The latter result means that the electrical potentials of twelve meridians were reflected by the function of the viscera and bowels.