A diagnosis catheter 1 for an interstitial cystitis is connected to a current perception threshold inspection apparatus 4 to diagnose an interstitial cystitis. A catheter body 11 is made of a soft flexible material and includes a bladder-dwelling distal end section A and a diagnosis section B adjacent the distal end section A at a proximal end side of the body 11. A core member 12 is made of a hard flexible material and is inserted into the diagnosis section B in the catheter body 11. An inflatable balloon 13 is mounted on an outer periphery around the bladder-dwelling distal end section A of the catheter body 11. A pair of electrodes are provided on an outer periphery of the diagnosis section B. Lead wires 15 are inserted into the core member 12 so that first ends of the lead wires 15 are connected to the electrodes 14 and second ends of the lead wires 15 are drawn out of a proximal end of the catheter body 11 to be connected to the current perception threshold inspection apparatus 4. A fluid supply passage 16 is provided in the catheter body 11 so that an end of the passage 16 is communicated to the balloon 13 and a proximal end of the passage 16 is communicated to an injection part 17.
