PURPOSE: To protect and endoscope from an impact due to a discharge and to prevent a damage by providing an opening to be positioned at a rear side from an electrode for discharge at a head part and to discharge a gas or a liquid including the gas onto the side surface of a probe main body.

CONSTITUTION: Plural openings 6 are provided in being positioned at the rear side from an electrode 4 for discharge and at a uniform angle interval onto the side surface of a probe 2 main body, and individual tubes 7 are connected to respective openings 6. An inserting part 11 of the endoscope is introduced into a body cavity 11, and the head of the inserting part 11 is made to advance near to a stone 13. In such a condition, a probe 1 is penetratingly inserted through a channel 14 for penetrating insertion of the endoscope, it is projected at a definites distance from the endoscope head, an air is fed from the base of the probe 1 into the tube 7, the air is discharged from respective openings 6, a voltage is impressed to the electrode 4 and the discharge is caused. At such a time, many bubbles 15 are generated, and the wall of an air layer is formed between the head of the probe 1 and the head surface of the endoscope inserting part 11. Consequently, at the time of the discharge, a shock wave (w) propagated under the water can be shielded, and it goes not reach the head surface of the endoscope inserting part 11.