An ophthalmologic apparatus comprises a light source 12, an optical measurement system 13 that radiates first light from the light source to inside an eye to be examined and guides first reflected light from the eye, an optical reference system (24, 22) that radiates second light from the light source to a reference surface and guides second reflected light from the reference surface, a photo detector 26 that detects interfering light between the first reflected light from the optical measurement system and the second reflected light from the optical reference system, and a processor that determines a position of a measuring portion of the inside of the eye based on the detected interfering light. The optical measurement system comprises an incident angle changing member 46 that changes an incident angle of the first light radiated to the eye within a predetermined angular range relative to an axis of vision of the eye.