The endoscope optical adapter includes a plurality of incident optical systems arranged such that each optical axis is spaced apart from the optical axis of the endoscope optical adapter by a predetermined distance, and the plurality of incident optical systems. An aperture stop corresponding to the incident optical system, and a relay lens that relays the incident light guided to the plurality of incident optical systems to the brightness stop, and along the incident direction of the incident light, the front side To the plurality of optical systems, the relay lens, and the aperture stop in this order, and a front light-shielding portion provided on the front side of the relay lens.本内視鏡用光学アダプタは、それぞれの光軸が前記内視鏡用光学アダプタの光軸より一定の間隔を開けて、偏心状態となるように配置される複数の入射光学系と、前記複数の入射光学系に対応した明るさ絞りと、前記複数の入射光学系に導かれた入射光を前記明るさ絞りへ中継する中継レンズと、を備え、前記入射光の入射方向に沿って、前側から、前記複数の光学系、前記中継レンズ、前記明るさ絞りの順に配置されると共に、前記中継レンズの前側に設けられる前側遮光部を有する。
