A motion detector 220 calculates the Doppler frequency shift amount based on the movement velocity of an eye E. A drive controller 230 calculates the modulation frequency of the intensity of output light M based on this Doppler frequency shift amount. A light source unit 201 outputs the light M in which the intensity is modulated with this modulation frequency. The light M is divided into a signal light S and a reference light R. Interference light L is generated by superimposing the signal light S passing through the eye E and the reference light R. Two polarized components of the interference light L have a phase difference of 180°, resulting from a quarter-wave plate 207. The polarized components L1, L2 which are divided by a polarization beam splitter 211 are detected by CCD 212, 213. A computer 250 forms a tomographical image based on these detection results.