An optical coherence tomography device (OCT) is capable of controlling a distance between an eye to be examined (object) and the OCT and accurately center-aligning the eye. A mire ring optical system emits a measuring mire ring light to an object to be examined. A dichroic mirror separates an optical path of illumination light reflected from the object from the optical path of the signal light originating from the tomographic image formation section and delivers a reflected image to an image formation section and a tomographic image formation section. An objective lens condenses light reflected from the object, and a controller calculates movement distance of the OCT from the difference between a position of the image of the mire ring light and a position of an optical axis of the OCT The OCT is then moved according to the calculated movement.
