The insertion device 1 includes a spiral tube 31 that is rotatable about a longitudinal axis and is detachably mounted. The insertion device 1 includes an insertion portion 3 having a predetermined flexibility and a drive source 72 that rotates the spiral tube 31. Even when the tube 31 and the portion 25 of the insertion portion 3 to which the spiral tube 31 is attached receive the external force to maintain the curved shape from the contacting body cavity wall, the rotation of the spiral tube 31 is not stopped by the driving force of the driving source 72. It is composed of a structure that is set so as not to bend beyond an arbitrary bending angle R. 挿入装置１は、長手軸回りに回転自在なスパイラルチューブ３１が着脱自在に装着され、所定の可撓性を備えた挿入部３と、スパイラルチューブ３１を回転させる駆動源７２と、を備え、スパイラルチューブ３１およびスパイラルチューブ３１が装着される挿入部３の部位２５は、接触する体腔壁から湾曲形状を維持しようとする外力を受けても駆動源７２の駆動力によってスパイラルチューブ３１の回転が停止しない任意の曲げ角度Ｒ以上に湾曲しないように設定された構造体により構成されている。
