1. An information displaying apparatus, comprising: an image input section that receives, as an input, a captured real-world image; a distance acquisition section that measures and acquires, for each of a plurality of objects shown in the captured real-world image, a horizontal distance in the real-world between the object and a viewpoint of the captured real-world image, the horizontal distance negating an elevation of the object with respect to the viewpoint in the real-world; a subject position and orientation acquisition section that acquires a position of the viewpoint in the real-world; an object positioning section that calculates and acquires, for each object of the objects, a real-world position of the object, the real-world position calculated based on the position of the viewpoint, the horizontal distance, a direction, and an angle of elevation of the object with reference to the viewpoint; an object information search section that searches, for each object of the objects, for a piece of information relating to the object using the real-world position of the object as a search key, and acquires the piece of information; an object superimposition section that outputs an image in which pieces of information corresponding to the objects are superimposed on the captured real-world image; and an information output control section that controls, for each of the objects, the piece of information output from the object superimposition section, wherein, the shorter the acquired horizontal distance is, the greater an information amount for the piece of information which is displayed in the image output from the object superimposition section is to be decided, for each of the objects, by the information output control section, and the information amount for the piece of information, for each of the objects, is determined based on a number of the objects and a proportion of the captured real-world image occupied by object areas of the objects, the piece of information corresponding to each object being displayed in an area of the captured real-world image other than the object areas.