PROBLEM TO BE SOLVED: To provide an endoscope capable of achieving both downsizing and robustness of the endoscope.SOLUTION: An endoscope (11) includes: a single lens (93) whose outer shape in a vertical direction with respect to the center of the lens is substantially quadrangular； an imaging element (33) arranged on a rear surface side opposite to an objective side of the single lens, whose outer shape in a vertical direction with respect to the center of the lens is substantially quadrangular, and whose length of one side is the same as the length of one side of the single lens； an element cover glass (43) which covers an imaging surface (41) of the imaging element, and whose outer shape in a vertical direction with respect to the center of the lens is the same as the outer shape of the imaging element； and a sheath (61) arranged coaxially with the center of the lens to surround the respective outside surfaces of the single lens, the element cover glass, and the imaging element, which is substantially in contact with the imaging element, and whose surrounding outer shape is circular.SELECTED DRAWING: Figure 37【課題】内視鏡の小型化と堅牢性の向上とを両立できる内視鏡を提供する。【解決手段】内視鏡（１１）は、レンズ中心に対して垂直方向の外形状が略四角形の単一レンズ（９３）と、単一レンズの対物側と反対の後面側に配置され、レンズ中心に対して垂直方向の外形状が略四角形であり、その一辺の長さが単一レンズの一辺の長さと同一である撮像素子（３３）と、撮像素子の撮像面（４１）を覆い、レンズ中心に対して垂直方向の外形状が撮像素子の外形状と同一の素子カバーガラス（４３）と、レンズ中心と同軸に配置され、単一レンズ、素子カバーガラス及び撮像素子の各外側面を包囲し、かつ撮像素子と略接し、包囲している外形状が円形のシース（６１）と、を備える。【選択図】図３７
