1. A display apparatus for displaying a three-dimensional image, comprising: a display module having a display surface on which pixels are arranged in matrix, parallax images being allotted to the pixels; an optical element facing the display module, having optical apertures arranged in association with the parallax images, and configured to project the parallax images to a near-side region and display one of first three-dimensional image in the near-side region and a second three-dimensional image in a far-side region located opposite the near-side region with respect to the display module; and a gap setting section configured to set a first optical gap between the optical element and the display surface to display the first three-dimensional image in the near-side region, the first optical gap having a first gap length longer than a reference distance which is determined depending on a position of the three-dimensional image, and a second optical gap between the optical element and the display surface to display the second three-dimensional image in the far-side region, the second optical gap having a second gap length being shorter than the reference distance.