An endoscope for treatment suitable to the treatment in a body cavity
comprises an elongated soft observing optical unit having at least an
observing optical system; and a unit inserting tool having a unit
inserting channel in which the observing optical unit is inserted and a
treatment tool inserting channel in which a treatment tool is inserted.
The unit inserting channel of the unit inserting tool has a branching
portion at which the unit inserting channel is branched into a first
inserting channel and a second inserting channel. An observing window
which is arranged at the end opening of the first inserting channel is
provided in a surface at the distal-end and an observing window which is
arranged at the end opening of the second inserting channel is provided
in a surface at the halfway portion. The unit inserting tool comprises an
optical unit guiding port for guiding the observing optical unit and at
least one treatment tool lead-in port in which a treatment tool is
inserted at the proximal end portion and a treatment tool lead-out port
which is communicated with the treatment tool inserting channel that
extends from the treatment tool lead-in port at least in one of the
surface at the distal-end and the surface at the halfway portion.