1. A fundus oculi observation device, comprising: a first image forming part configured to optically obtain data and, based on the obtained data, form a fluorescence image of a fundus oculi of an eye administered with a fluorescent agent in advance; a second image forming part configured to optically obtain data and, based on the obtained data, form a tomographic image of the fundus oculi; a display part; and a controller configured to cause the display part to display the fluorescence image formed by the first image forming part side by side with the tomographic image formed by the second image forming part, and display cross-sectional-position information that represents a cross-sectional position of the tomographic image in the fluorescence image so as to overlap the fluorescent image.