Even if a divided wavelength plate filter is mounted, it is possible to reliably display a three-dimensional image or perform a displaying operation on from one screen to a plurality of screens. In a display device, the relative positions of an image display section and a divided wavelength plate filter for rotating polarized light from image information at a first segment in a direction that is different from the direction of polarized light from image information at a second segment can be adjusted. At the time of positional adjustment, the display device displays a position adjustment pattern (112) having colors, figures, characters, symbols, diagrams, or designs, or combinations thereof which differ from each other depending on the segment.