And an insert body which extends along a longitudinal axis, an insertion portion to be inserted into the lumen, and an operation unit provided in the proximal direction side of the insertion portion, the endoscope, along the longitudinal axis and a fin portion which extends in a spiral shape, and a, and a mounting unit provided on the outer circumference side of the insertion portion in a state of being rotatable about the longitudinal axis relative to the insert body. Also, by rotating the gear axis, a rotary gear for rotating the longitudinal axis of the mounting unit, endoscope, the inside of the operating portion and inside of the insert body from the tip of the insertion portion through, and a, and a built-extending member that extends along the longitudinal axis. The insertion body includes a partition member that separates between the rotary gear and said internal extending member.内視鏡は、長手軸に沿って延設される挿入本体を備え、管腔に挿入される挿入部と、 前記挿入部より基端方向側に設けられる操作部と、前記長手軸に沿って螺旋状に延設されるフィン部を備え、前記挿入本体に対して長手軸回りに回転可能な状態で前記挿入部の外周方向側に設けられる装着ユニットと、を備える。また、内視鏡は、ギア軸回りに回転することにより、前記装着ユニットを前記長手軸回りに回転させる回転ギアと、前記挿入部の先端部から前記挿入本体の内部及び前記操作部の内部を通って、前記長手軸に沿って延設される内蔵延設部材と、を備える。前記挿入本体は、前記内蔵延設部材と前記回転ギアとの間を分離する仕切り部材を備える。
