In the insertion portion of the insert, the moving member comes into contact with the outer peripheral surface of the cylindrical member. When the driving force is transmitted from the cylindrical member by rotation of the longitudinal axis of the longitudinal axis of the cylindrical member, the moving member rotates about the rotation axis parallel to the longitudinal axis, and moves about the axis of the longitudinal axis.In the insert portion, the coating covers the moving member from the outer circumference side, and the film urges the moving member toward the longitudinal axis to push the moving member against the outer peripheral surface of the cylindrical member.挿入具の挿入部では、円筒部材の外周面に移動部材が接触する。前記移動部材は、前記円筒部材の長手軸の軸回りの回転によって前記円筒部材から駆動力が伝達されることにより、前記長手軸に平行な自転軸を中心として回転するとともに、前記長手軸の前記軸回りに移動する。前記挿入部では、被膜が前記移動部材を外周側から覆い、前記被膜は、前記移動部材を前記長手軸へ向かって付勢することにより、前記移動部材を前記円筒部材の前記外周面へ押圧する。
