A three-dimensional image display apparatus includes a light source and an optical system including a light modulation unit having pixels for generating a two-dimensional image by modulating light from the light source by the respective pixels and emitting a spatial frequency in the generated two-dimensional image along a diffraction angle corresponding to diffraction orders generated from the respective pixels, a Fourier transform image formation unit for performing Fourier transform on the spatial frequency in the two-dimensional image to generate Fourier transform images corresponding to the diffraction orders, a Fourier transform image selection unit for selecting a Fourier transform image corresponding to a desired diffraction order among the Fourier transform images, and a conjugate image formation unit for forming a conjugate image of the selected Fourier transform image, and further includes a semi-transmissive mirror for changing a light ray travelling direction emitted from the optical system.