Provided is an operation microscope capable of obtaining bright and wide range red reflex on an observation image. Further, an operation microscope suitable for an observation of a retina and a vitreous body is provided. A pair of deflection members composed of two deflection mirrors are provided as a deflection means for deflecting illumination light guided from a light source to the vicinity of an optical axis of an observation optical system and guiding it to an eye to be operated through an objective lens. The deflection mirrors are disposed to sandwich the optical axis therebetween and simultaneously guide the illumination lights to the eye to be operated at substantially the same oblique angles with respect to the optical axis from the respective opposite sides. In addition, a stereo variator is made insertable onto the observation optical axis, so that relative positions of optical axes of right and left observation fluxes can be changed.