An image-acquisition device is consists of a single objective optical system an image-acquisition element that acquires an image of an optical image of an object formed by the objective optical system an optical component that can be inserted into and removed from the optical axis of the objective optical system, at an intermediate position on the optical axis and a moving mechanism that moves the optical component between a position on the optical axis of the objective optical system and a position off the optical axis. The optical component has a deflecting surface for deflecting the optical axis of the objective optical system and a refracting surface having power.
