The insertion portion provided in the insertion device is provided between the tube low flexure portion (55) and the tube high flexible portion (56) in the flexible tube (15), and extends from the proximal direction side toward the distal direction side And a first flexible change portion (57) whose flexibility changes. The insertion part is provided between the member low flexure part (65) and the member high flexure part (66) in the built-in member (47), and is inserted into the flexible high flexure part (66) from the proximal direction side toward the distal direction side And a second flexible change part (67) whose property changes. The second flexible change part (67) is displaced with respect to the first flexible change part (57) in the longitudinal direction, and a desired flexibility distribution in the longitudinal direction .挿入機器に設けられる挿入部は、可撓管(15)において管低可撓部(55)と管高可撓部(56)との間に設けられ、基端方向側から先端方向側に向かって可撓性が変化する第1の可撓性変化部(57)を備える。前記挿入部は、内蔵部材(47)において部材低可撓部(65)と部材高可撓部(66)との間に設けられ、前記基端方向側から前記先端方向側に向かって可撓性が変化する第2の可撓性変化部(67)を備える。前記第2の可撓性変化部(67)は、長手方向について、前記第1の可撓性変化部(57)に対してずれて位置しており、長手方向についての所望の可撓性分布を実現する。
