Inserting instrument, rotary unit and inserting apparatus

An inserting instrument to which a rotary unit including a spiral tube is rotatably attached around a longitudinal axis,

• the inserting instrument comprising:
• an inserting section extended along the longitudinal axis, and inserted through the rotary unit;
• a bending section provided in a distal portion of the inserting section;
• a first flexible tube section provided on a proximal side with respect to the bending section in the inserting section, and having a flexibility lower than each the spiral tube and the bending section;
• a second flexible tube section provided on the proximal side with respect to the first flexible tube section in the inserting section, and covered by the spiral tube on an outer peripheral side in a state where the rotary unit is attached to the inserting section, the second flexible tube section having a flexibility lower than a flexibility of the spiral tube and the flexibility equal to that of the first flexible tube section or higher than that of the first flexible tube section in a state where the second flexible tube section is not covered by the spiral tube, the flexibility of the second flexible tube section being formed to be lower than the first flexible tube section in a state where the second flexible tube section is covered by the spiral tube;
• and
• a third flexible tube section provided on the proximal side with respect to the second flexible tube section in the inserting section, having a flexibility lower than the first flexible tube section, and formed in a state where the flexibility decreases from a distal side toward the proximal side,
• wherein a flexibility at a proximal end of the third flexible tube section is adjusted to be lowest in the first flexible tube section, the second flexible tube section and the third flexible tube section, and
• the flexibility of the second flexible tube section in the state where the second flexible tube section is covered by the spiral tube is adjusted to be higher than the flexibility at the proximal end of the third flexible tube section.