An apparatus for measuring a distance between eye components includes an interference optical system including a light source, a beam splitter splitting light into first and second light, a projection optical system projecting the first and/or second light onto the eye, a photo-receiving optical system synthesizing the first light reflected from the eye and the second light, and an optical-path-length varying optical member disposed on one of light optical paths to be movable in an optical axis direction and adjusting a relationship between light optical path lengths, a mechanism obtaining a travel position of the member, and a unit controlling a driving unit to move the member toward one direction of the axis direction and toward the reverse direction, obtaining interference signals respectively while moving the optical member toward the directions, and calculating distances between the components based on the travel position where the signals are obtained.
