To provide an instrument for the topographic measurement of an eye structure based on short coherence interference measurement without causing any measuring error of the structure due to longitudinal and lateral motions of the eyes in a signal recording process.

An influence caused by the longitudinal motions of the eyes is corrected by sighting a reference light beam on the top of the cornea regardless of a measuring light beam and reflecting it there, and the influence caused by the longitudinal motions of the eyes is miniaturized by discriminating and correcting lateral control deviation by checking the lateral positions of the eyes by recording the light reflected on the top of the cornea by directions by a diode array of four-quadrant diode.