This invention provides a polarization means capable of obtaining an always clear three-dimensional image easily, correctly, and quickly and a position holding mechanism. A polarizing plate has areas for the left eye and the right eye where respective polarized lights separated by a first half wave plate enter. A second half wave plate for rotating the polarized lights in a direction opposite to that of the first half wave plate is disposed on an image display surface side for the right eye side area of the polarizing plate. A polarizing plate fixture with an arm part for holding the polarizing plate in a predetermined position is also provided.