Provided is a catheter for safely measuring electric potential which can be inserted inside a heart chamber in combination with an ablation catheter with a balloon and which can prevent abnormal heat generation by an electrode for measuring electric potential even if a high frequency current passes through. The catheter for measuring electric potential is provided with: a shaft comprising an electrode for measuring electric potential a metal section having a length of at least 2 mm and a lumen that passes through the distal end from the proximal end in a longitudinal direction and a metal wire that passes through the abovementioned lumen and is connected to the abovementioned metal section.
