The heat generated by the light guide passing through the vicinity is concentrated and transmitted to the acute angle portion connected to the bottom surface from the conical surface of the lens constituting the observation window of the conical surface for performing side observation on the endoscope insertion portion It affects the lens.The endoscope apparatus includes a first lens of a front observation window for observing an insertion direction to be inserted into a lumen and a second lens of a truncated conical shape for observing a visual field region of a side observation window for observing a direction crossing the insertion direction 2 lens are disposed, heat generated by the light guiding of the light guiding portion passing near the second lens and conducted to the second lens is radiated to the frame member, and the heat is radiated to the frame member, A thermal influence alleviating unit for relieving a local temperature difference in the heat affecting zone.内視鏡挿入部に側方観察を行うための円錐面の観察窓を構成するレンズの円錐面から底面に繋がる鋭角部分に、近傍を通過するライトガイドが発生する熱が集中して伝導されてレンズに影響を与える。内視鏡装置は、管腔内に挿入される挿入方向を観察する前方観察窓の第1レンズと挿入方向と交差する方向を観察する側方観察窓の視野領域を観察する円錐台形状の第2レンズとが配置される突出部で、第2レンズの近傍を通過する導光部の導光に伴い発生して第2レンズに伝導される熱を枠部材に放熱して、第2レンズ内における局所的な温度差を緩和する熱影響緩和部を備える。
