The first image sensor 32l that receives the first optical image formed by the first objective optical system 31l and the second image sensor 32r that receives the second optical image formed by the second objective optical system 31r. The respective light receiving surfaces 32la and 32ra are positioned and fixed by bonding with respect to a single centering glass 34 disposed on the optical path of the first and second optical images, and the centering glass 34 is interposed therebetween. The first and second image sensors 32l and 32r are held by the holding frame 35. 第１の対物光学系３１ｌが形成する第１の光学像を受光する第１の撮像素子３２ｌと、第２の対物光学系３１ｒが形成する第２の光学像を受光する第２の撮像素子３２ｒと、の各受光面３２ｌａ，３２ｒａ側を、第１，第２の光学像の光路上に配置される単一の芯出しガラス３４に対して接着によって位置決め固定し、この芯出しガラス３４を介して第１，第２の撮像素子３２ｌ，３２ｒを保持枠３５に保持する。
