1. A naked-eye stereoscopic display apparatus comprising: a display device in which a plurality of pixels are arrayed in a horizontal direction and a vertical direction, whereby the display device assigns respective pixels of video data composed of a plurality of viewpoint images to the plurality of pixels, thereby displaying the respective pixels of pixel data; an optical member that has a plurality of optical elements periodically arrayed therein, arranged on the display device in a state where a periodic direction of the optical elements is inclined with respect to the horizontal direction of pixels in the display device, and configured to divide the plurality of viewpoint images displayed on the display device into a plurality of different viewpoint directions, and to present the divided viewpoint images; and a viewpoint adjustment unit which within a maximum predetermined viewing angle defined by two viewpoint images with the largest parallax, defines a first angular region in which there is a high possibility that a viewer's eyes may be present when observing the display device and a second angular region in which there is a low possibility that a viewer's eyes maybe present, and which is configured to reduce the parallax between adjacent viewpoint images displayed in the first angular region more than the parallax between adjacent images in the second angular region.