PURPOSE: To shorten the total working time of an operation which uses an endoscope by omitting the labor otherwise required for refitting of the cords for high-frequency current feeding at the time of replacement of the treatment tool under the operation, and allowing the operation to go on smoothly.

CONSTITUTION: The body 2a of a treatment tool is formed from a reduction tube 5, which has a connection part for cords to feed high-frequency current, and either of hand instruments 6, 7 to be inserted removably into the reduction tube 5, wherein further a connecting mechanism is furnished to transmit the high-frequency current from the tube 5 to either hand instrument 6, 7.