An intracardiac defibrillation catheter capable of surely supplying electric energy necessary and sufficient for defibrillation and conducting a defibrillation treatment without causing burn on the body surface of a patient.The intracardiac defibrillation catheter is equipped with an insulated tube member 10 having a multi-lumen structure, a handle 20 connected to a proximal end of the tube member 10, a DC electrode group 31G installed in a distal region of the tube member 10, a second DC electrode group 32G installed on the tube member towards proximal direction from the first DC electrode group, a first lead wire group 41G composed of lead wires 41 connected to the respective electrodes making up the first DC electrode group 31G, and a second lead wire group 42G composed of lead wires 42 connected to the respective electrodes making up the second DC electrode group 32G, wherein the first lead wire group 41G and the second lead wire group 42G respectively extend into different lumens 11, 12 of the tube member 10.
