PROBLEM TO BE SOLVED: To provide an in vivo potential measuring instrument capable of accurately measuring a potential of a cautery site when the periphery of an inner wall surface of an organ is cauterized in an ablation treatment, etc.SOLUTION: An in vivo potential measuring instrument which is inserted into an organ of a living body for measuring a potential of a predetermined site on an inner wall surface of the organ includes: a hollow bag-like insulating member； and a hollow tubular member connected to a first electrode disposed in the hollow part of the insulating member and the insulating member. A conductive fluid is injected into the hollow part of the insulating member through the hollow tubular member, and in the state that the outer peripheral surface of the insulating member is brought into contact with the inner wall surface of the organ, a potential of the site in contact is measured by the first electrode. A second electrode electrically connected to the fluid that exists inside the hollow tubular member is disposed in the hollow tubular member, and the second electrode adjusts a potential of the fluid.SELECTED DRAWING: Figure 5COPYRIGHT: (C)2020,JPO&INPIT【課題】アブレーション治療等で、器官の内壁面の周囲を焼灼した際の焼灼部位の電位を、正確に計測することができる生体内電位計測器を提供する。【解決手段】本発明の生体内電位計測器は、生体の器官内に挿入して、該器官の内壁面における所定部位の電位を計測する生体内電位計測器であって、中空袋状の絶縁性部材と絶縁部材の中空部分の中に配置された第１の電極と絶縁性部材に結合した中空管状部材とを備え、中空管状部材を介して、絶縁性部材の中空部分に導電性の流動体が注入され、絶縁性部材の外周面を器官の内壁面に接触させた状態で、該接触した部位の電位を第１の電極で計測し、中空管状部材には当該中空管状部材の内部に存する流動体と電気的に接続された第２の電極が配置されており、第２の電極は流動体の電位の調整を行う。【選択図】図５
