The stereoscopic image display device includes: an observer position measuring unit which measures the observing position of the observer; an image processing unit which calculates the relative position of the observing position of the observer and the stereoscopic display panel, calculates the luminance adjustment amount suited for stereoscopic image display for the relative position, and performs luminance adjustment processing on the image data according to the luminance adjustment amount; and a stereoscopic display panel unit which projects the image data on which the luminance adjustment processing is performed to the right eye and the left eye of the observer via the stereoscopic display panel.