A liquid crystal light valve projection type image display apparatus comprises an electro-optic element and a Schlieren optical system. The electro-optic element has a liquid crystal layer having a dielectric and optical anisotropy. An electric field having a spatial intensity distribution according to an image signal is applied to said liquid crystal at a spatial period, so that a spatially phase-modulated phase diffraction grating is formed in the liquid crystal layer. Thus, a projected image in enlarged form is obtained. The fact that the electric field with a spatial period is applied to the liquid crystal leads to a constant light diffraction angle, and the modulation of the diffraction light intensity in the applied electric field enables an image corresponding to the input image signal to be projected at high light utilization.