A kind for the treatment of tool endoscope has a conduit and guide sheath. Conduit allows insertion section to be inserted, so that the front end of the distal end insertion part of front end side and side observe that the first distal end passes through the first distal end observation optical system and protrudes from the first distal side endurance by using the observation of the distal end of endoscope or the insertion section of front end side and insertion in the farend state of the endoscope of observation optical system, the internal diameter of the guide sheath, insertion section is allowed to be inserted in this way, so that distal end insertion part is exsertile from the second distal end, and it is inserted into conduit and the distal end of the second conduit is made to be exsertile from the first distal side endurance
