PROBLEM TO BE SOLVED: To provide a safe in-vivo impedance measuring method capable of accurately evaluating a change in extracellular fluid.SOLUTION: An in-vivo electrode 10 is arranged inside a living body, and a measurement reference electrode 40 is arranged on a surface 60 of the living body. A first voltage V1 generated when a first external resistor Rg1 is connected in parallel between the in-vivo electrode and the measurement reference electrode, and a second voltage V2 generated when a second external resistor Rg2 is connected in parallel are measured. On the basis of a voltage ratio V1/V2 of the first voltage V1 to the second voltage V2, in-vivo impedance Rb is measured.SELECTED DRAWING: Figure 2COPYRIGHT: (C)2020,JPO&INPIT【課題】安全で、かつ、細胞外液の変化を精度よく評価することができる生体内インピーダンス測定方法を提供する。【解決手段】生体の内部に体内電極１０を配置するとともに、生体の表面６０に測定基準電極４０を配置し、体内電極と測定基準電極との間に、第１の外部抵抗Ｒg1を並列接続したときに生じる第１の電圧Ｖ１、及び第２の外部抵抗Ｒg2を並列接続したときに生じる第２の電圧Ｖ２を測定し、第１の電圧Ｖ１及び第２の電圧Ｖ２の電圧比Ｖ１／Ｖ２に基づいて、生体内のインピーダンスＲbを測定する。【選択図】図２
