A method for judging whether obtainment of information on a three-dimensional image of a given portion of an examinee's eye that is obtained by OCT (Optical Coherent Tomography) is successful or not, the method involves processing the three-dimensional image information on the given portion that is obtained using an OCT optical system, where the OCT optical system is arranged to obtain a tomographic image of the examinee's eye, and obtaining an OCT front image of the given portion; and detecting a positional deviation of the OCT front image by image processing to judge whether the obtainment of the three-dimensional image information is successful or not based on a result of the detection.