1. A three-dimensional display device for displaying a three-dimensional image, comprising: a gaze point obtaining unit configured to obtain a position of a gaze point of a viewer; a fusional area determination unit configured to determine a fusional area where binocular fusion is allowed, based on the obtained position of the gaze point; a correction unit configured to correct the three-dimensional image so as to suppress display of an object which is included in the three-dimensional image outside the fusional area; and a display unit configured to display the corrected three-dimensional image.