It is made possible to correct a positional gap between an optical system and an eye of an observer appropriately.Based on an eyeball position of the eye of the observer, a positional relationship between the optical system, which leads an image displayed on a display element to the eye of the observer, and the eye of the observer, that is, a positional gap therebetween is detected. Based on the positional relationship detected in such a manner, the positional relationship between the optical system and the eye of the observer is corrected. For example, the positional gap is electronically corrected by performing shift control of a position of the image displayed on the display element. Also, for example, the positional gap is mechanically corrected by performing shift control of the optical system including the display element.