An optical unit concentrates light beams from measurement-light paths at first and second irradiation positions on an eyeground. Next, a control unit controls a scanning unit so that the light beams concentrated at the first and second irradiation positions are scanned in first and second scanning areas of the eyeground and so that the first and second scanning areas overlap to form an overlap area. A tomographic-information acquisition unit acquires first tomographic information and second tomographic information in the first and second scanning areas from interference light. Third tomographic information is acquired from the first tomographic information and the second tomographic information in the first and second scanning areas on the basis of the first tomographic information and the second tomographic information in the overlap area.