A method of observing a three-dimensional image of an examinee's eye to be examined, includes: obtaining a first three-dimensional image which is a three-dimensional image of an anterior segment of the examinee's eye by optical coherence tomography for obtaining a tomographic image by converging a measurement light on the anterior segment of the examinee's eye; obtaining a second three-dimensional image which is a three-dimensional image of a fundus of the examinee's eye by optical coherence tomography for obtaining a tomographic image by converging the measurement light on the fundus of the examinee's eye by a timing different from a timing of obtaining the first three-dimensional image; constructing a three-dimensional eyeball image of the examinee's eye through image processing based on the obtained first and second three-dimensional images; and displaying the constructed three-dimensional eyeball image on a monitor.