By being relaxed or pulled by operation of a treatment instrument operation unit, the endoscope apparatus comprises a bending operation wire for bending the bending portion treatment instrument. Provided in the proximal direction and the wire side of the die 1, from the wire portion of the first wire portion of the second higher rigidity than the wire section of the first, the bending operation wire, the first wire and a wire bonding portion for bonding between the wire portion and the second part, during the procedure the proximal end of the treatment instrument bending portion is positioned toward the distal end side of the tip of the endoscope insertion portion , I provided with a stiffness change wire the wire junction is located in the proximal direction side of the proximal end of the endoscope bending portion.内視鏡装置は、処置具操作部での操作によって牽引又は弛緩されることにより、処置具湾曲部を湾曲させる湾曲操作ワイヤを備える。前記湾曲操作ワイヤは、第1のワイヤ部と、前記第1のワイヤ部より基端方向側に設けられ、前記第1のワイヤ部より剛性が高い第2のワイヤ部と、前記第1のワイヤ部と前記第2のワイヤ部との間を接合するワイヤ接合部とを備え、前記処置具湾曲部の基端が前記内視鏡挿入部の前記先端より先端方向側に位置している処置時に、前記ワイヤ接合部が前記内視鏡湾曲部の基端より基端方向側に位置している剛性変化ワイヤを備える。
