A first bending portion 30 actively bending in conjunction with the bending operation in the operation portion, and a second bending portion 30 disposed on the proximal end side of the first bending portion and bendingly passively bending by an external force 40 of the second bending portion 40 and the flexible tube portion 7 connected to the proximal end side of the second bending portion 40 in the insertion portion 2, the bending rigidity of the distal end side is higher than the bending rigidity of the proximal end side (The first and second flexes 41, 51) configured so as to be higher in the second bending portion 40 and the flexible tube portion 7, and the flexural rigidity of the spiral tube portion is changed By setting the boundary (the boundary between the first and second flexes 41, 51) on the distal end side of the flexible tube portion 7, bending of the bending portion is prevented and good insertion property of the insertion portion is realized.操作部における湾曲操作に連動して能動的に湾曲動作する第1の湾曲部30と、第1の湾曲部の基端側に配設されて外力によって受動的に湾曲動作する第2の湾曲部40と、第2の湾曲部40の基端側に連設する可撓管部7と、を挿入部2に備えた内視鏡1において、先端側の曲げ剛性が基端側の曲げ剛性よりも高くなるよう構成した一連の螺旋管部(第1,第2のフレックス41,51)を第2の湾曲部40及び可撓管部7に配設し、螺旋管部の曲げ剛性が変化する境界(第1,第2のフレックス41,51の境界)を、可撓管部7の先端側に設定することにより、湾曲部の屈曲を防止して挿入部の良好な挿入性を実現する。
