1. A fundus oculi observation device comprising: a first image forming part configured to optically acquire data and form a 2-dimensional image of a surface of a fundus oculi of an eye based on the data; a second image forming part configured to optically acquire data and form a tomographic image of the fundus oculi based on the data; a display; a controller configured to cause the display to display the 2-dimensional image and the tomographic image side by side; and a designating part configured to designate a partial region of the displayed tomographic image, wherein the controller finds a position within the 2-dimensional image corresponding to the designated partial region, and displays designated-position information in a superimposed state on the position within the 2-dimensional image.