PROBLEM TO BE SOLVED: To provide an endoscope system in which an observable range of an observation object is not narrowed by a hood when the hood is mounted on a distal end part of an insertion part.SOLUTION: An endoscope system includes: an endoscope 10 which is provided with an observation optical system 19 whose optical axis is eccentric to the center point 18 of a distal end face on the distal end face 17 of an insertion part 12, and provided, inside the insertion part, with an imaging element 21 for which the center of an imaging surface 22 forming a rectangle is positioned on the optical axis and the midpoint of a pair of long sides of the rectangle is positioned on one straight line extending in a radial direction from the center point when viewed in the optical axis direction and a cylindrical hood 25 which is attachable and detachable to/from the distal end part of the insertion part and has an annular projection part 28. A distance in the straight line direction from the center point to the midpoint of one long side is longer than a distance in the straight line direction from the center point to the midpoint of the other long side, and the annular projection part is turned to such a shape that it is positioned outside of the observation field of the observation optical system when the hood is mounted on the distal end part of the insertion part.COPYRIGHT: (C)2013,JPO&INPIT【課題】挿入部の先端部にフードを装着したときに、フードによって観察対象の観察可能範囲が狭められることがない内視鏡システムを提供する。【解決手段】挿入部12の先端面17に光軸が先端面の中心点18に対して偏心する観察光学系19を設け、長方形をなす撮像面22の中心が光軸上に位置し、かつ、光軸方向に見たときに長方形の一対の長辺の中央点が中心点から放射方向に延びる一本の直線上に位置する撮像素子21を挿入部内に設けた内視鏡10と、挿入部の先端部に着脱可能で環状突出部28を有する筒状のフード25と、を備え、中心点から一方の長辺の中央点までの上記直線方向の距離が、中心点から他方の長辺の中央点までの上記直線方向の距離より長く、環状突出部を、フードを上記挿入部の先端部に装着したときに観察光学系の観察視野外に位置する形状とした。【選択図】図5
