A liquid junction potential between the KCl solution in the glass-capillary electrode and Ringer's-, NaCl- and KCl solution was measured with a tube-potentiometer. A negative charge of the liquid junction potential. The decreasing grade of the mobility and ionic activity can be estimated from the measured potential between the KCl solutions inside and outside the capillary. From these estimation, the potential can be calculated by the Henderson's rquation.