PURPOSE: To enable the treating of a lesion tissue as a whole with a limited side effect to a normal tissue excluding the lesion tissue simultaneously with a treatment of a local lesion tissue by combining a treatment by current energization with that by a drug solution for antipathogens.

CONSTITUTION: A catheter 8 is inserted through a forceps channel 2 and a tip of an endoscope 4 inserted into a body cavity is brought closer to a desired cancerous tissue 15. A hollow path 10 of the catheter 8 is filled with an carcinostatic solution ionized by a syringe 11. The tip 5 of the catheter 8 is protruded ahead of the tip of the endoscope 4 from a forceps opening 14 at the tip of the endoscope 4 to stick into the cancerous tissue 15. Then, a power source 9 is turned ON to apply a voltage between first and second electrodes 6 and 7. NaCl and H2O as main components in vivo are dissociated. HCl as strong acid is generated in the perimeter of an anode by an electric field in the cancerous tissue 15 as caused by the voltage applied and NaOH as strong alkali is generated in the perimeter of a cathode. The cancerous tissue 15 develops necrosis by toxicity of the strong acid and alkali and further, degeneration, vanishing or the like of the cancerous tissue 15 occurs by toxicity of the Cl2 at the anode.