The purpose of the present invention is to provide a balloon-type ablation catheter with which it is possible to measure the electric potential around the entire circumference of a pulmonary vein at a position close to the left atrium via an electrode fitted to the catheter tip portion of an electrode catheter inserted into a shaft in a state in which the balloon is pressed against the periphery of an opening of the pulmonary vein. This balloon-type ablation catheter is provided with: a multi-lumen catheter shaft (10) formed from a plurality of lumens (11-17) including liquid-feeding lumens (13), (16) and an electrode catheter insertion lumen (12)； a tip tube (30) fitted to the tip of the catheter shaft (10)； a balloon (50) fitted to the tip portion of the catheter shaft (10)； and an electrode (70) for applying a high-frequency current, said electrode (70) being provided to the balloon (50). A side-hole (32) is formed in the tip tube (30). The side-hole (32) is connected to the electrode catheter insertion lumen (12) and opens at a side peripheral surface of the tip tube (30).
