An observation device includes: a holding board that holds an observation container accommodating a cornea for transplantation to be observed; a specular reflection optical system including an illumination optical system and an imaging optical system, which include a light source and an imaging unit, for observing the cornea for transplantation; and an auxiliary light source that illuminates the cornea for transplantation from the back and has an auxiliary illumination optical axis inclined with respect to an observation base axis that divides in half an intersecting angle of the illumination optical axis of the illumination optical system and an imaging optical axis of the imaging optical system, wherein the auxiliary light source is installed in a freely pivoting manner about a predetermined rotation axis so that a relative inclination angle with respect to the observation base axis of the auxiliary illumination optical axis can be continuously changed.