A treatment endoscope includes that a body cavity insertion portion which includes a main body distal hard portion, and a main body curving portion provided to a proximal side of the main body distal hard portion, one or more treatment arm/arms projecting to a distal side from the main body distal hard portion, each of the treatment arm/arms including a curving mechanism, an operation portion provided to the proximal side of the body cavity insertion portion, and an observation section configured to image a field of view in a body cavity, the observation section including an imaging section provided within the main body distal hard portion. The treatment endoscope includes that an operation portion attaching/detaching mechanism configured to removably attach the operation portion to the body cavity insertion portion, and an observation section attaching/detaching mechanism configured to removably attach the observation section to the body cavity insertion portion.
