This invention aims to provide a high-safety catheter for electric potential measurement, which can be inserted into a heart chamber together with an ablation catheter with balloon, so as to prevent electrodes for electric potential measurement from abnormal heating even when a high-frequency electric current is supplied to the electrodes.A catheter for electric potential measurement comprising a shaft and a metal wire is provided. The shaft has electrodes for electric potential measurement, a metal portion which is above 2mm in length, and a lumen extending from a proximal end to a distal end in the length direction thereof. The metal wire is inserted to the lumen and connected with the metal portion.本發明之目的在於提供一種高安全性的電位測定用導管,其可與附有氣球之電燒導管一起插入心腔內,即使進行高頻電流之通電,仍可防止電位測定用電極之異常發熱。本發明提供一種電位測定用導管,其具備:軸,其具有電位測定用電極、長度為2mm以上之金屬部、及從長度方向之近位端貫穿至遠位端的管腔;以及金屬線,其插通於該管腔內,並連接於該金屬部。1...電位測定用導管2...電位測定用電極3...軸4...電位測定用裝置連接用連接器5...遠位端金屬部
