To provide a highly reliable projection display device capable of being used for a long period of time without deterioration of a particular liquid crystal light valve, desirably, without any variation in color balance with time, even if a light source having a deviation of light intensity distribution is used. A projection display device in which a liquid crystal light valve includes a liquid crystal layer including TN liquid crystals having a twisted angle of substantially 90 degrees, with a polarization direction of a primary light L.sub.B incident upon the liquid crystal layer and an alignment direction of liquid crystal molecules disposed at a primary-light incident surface of the liquid crystal layer being substantially perpendicular to each other.