A liquid crystal display panel includes a first substrate and a second substrate, at least one of which possesses light transmissivity, each having an electrode layer formed thereon, the electrode layers confronting each other, and a liquid crystal layer sandwiched between the first substrate and the second substrate, divided into plural regions, and including liquid crystal molecules. The liquid crystal molecules are oriented in the same direction in each of first regions, and in a different direction in second regions each located between two adjacent first regions. The second regions are spaced at a regular periodicity. Without an electric field applied to the liquid crystal layer, the different orientations of the liquid crystal molecules create differences in the refractive indices at which the light is transmitted so as to serve as a phase grating the diffracts incident light. When an electric field is applied, the difference in the refractive indices decreases, and the incident light is not diffracted but propagates as is through the panel. The liquid crystal display panel may be incorporated into a projection display apparatus having a light source and projection lens.