PROBLEM TO BE SOLVED: To provide an endoscope apparatus configured such that a distal-end of an endoscope insertion portion can smoothly be fit into small-diameter bile and pancreatic ducts, that the visibility of an observation view field can be enhanced, and that manipulations performed with treatment instruments can easily be observed.SOLUTION: The endoscope apparatus includes an endoscope insertion portion, an operation portion provided at the side of the base end of the endoscope insertion portion, an operating wire 57 for transmitting an operation of the operation portion with a tensile force, and a bending portion provided at a distal-end side of the endoscope insertion portion to be subjected to a bending operation performed with the operating wire 57. The bending portion is such that, when a bending-portion cross-section defined by a plane perpendicular to a longitudinal axis of the endoscope insertion portion is divided into two regions by a straight line 61 passing through the center 59 of the bend-portion cross-section, the bend-portion cross-section is dividable into a first region 63 in which the operating wire 57 is present and a second region 65 in which the operating wire 57 is not present. A distal-end projection domain is obtained by projecting the first region 63 in which the cross-section of the operating wire 57 is present onto a distal-end surface at a distal-end of the endoscope insertion portion. The distal-end projection domain is protruded from the distal-end of the endoscope insertion portion outward in a direction of the longitudinal axis of the endoscope insertion portion. An observation window 39 for observing an object is arranged in the protruded distal-end projection domain.COPYRIGHT: (C)2012,JPO&INPIT【課題】内視鏡挿入部の先端を細径の胆・膵管内へスムーズに挿入でき、しかも、観察視野の視認性を高め、且つ処置具による手技を容易に観察できる内視鏡装置を提供する。【解決手段】内視鏡装置は、内視鏡挿入部と、内視鏡挿入部の基端側に設けられた操作部と、操作部の操作を張力によって伝達する操作ワイヤ57と、内視鏡挿入部の先端側に設けられ操作ワイヤ57によって湾曲操作される湾曲部とを備える。この湾曲部は、内視鏡挿入部の長手軸と直交する平面で規定される湾曲部断面において、湾曲部断面の
