For appropriately obtaining the tomographic image and the layer thickness map are provided in a short period of time regardless of involuntary eye movement, when the tomographic image is to be obtained in a specific scan pattern, a 3D tomographic image is first obtained by 3D scan, and then a tomographic image of a desired part is extracted from the image in accordance with the specific scan pattern. Further, based on the obtained 3D tomographic image, a sector for layer thickness map display, a main scanning line, and a sub-scanning line, which are displayed on a fundus image, are set movable, and tomographic images taken along both the scanning lines after the movement are obtained. The sector having a center corresponding to the intersection between those scanning lines and the layer thickness map are recalculated and displayed so as to follow the intersection.