The insertion device includes a first flexible tube portion having lower flexibility than a spiral tube and a second flexible tube portion which is lower than the spiral tube in a state where the spiral tube is not covered and which is the same as the first flexible tube portion Or a second flexible tube portion having higher flexibility than the first flexible tube portion. The flexibility of the second flexible tube portion is lower than that of the first flexible tube portion by covering the spiral tube on the outer peripheral direction side. The insertion device includes a third flexible tube portion that is lower in flexibility than the first flexible tube portion toward the proximal direction side of the second flexible tube portion.挿入機器は、スパイラルチューブより可撓性が低い第1の可撓管部と、前記スパイラルチューブが被覆されていない状態において、前記スパイラルチューブより低く、かつ、前記第1の可撓管部と同一又は前記第1の可撓管部より高い可撓性を有する第2の可撓管部と、を備える。前記第2の可撓管部は、前記スパイラルチューブが前記外周方向側に被覆されることにより、前記第1の可撓管部より可撓性が低くなる。前記挿入機器は、前記第2の可撓管部より前記基端方向側に、前記第1の可撓管部より可撓性が低い第3の可撓管部を備える。
