To provide a picture display device and an illuminator having a diffractive optical element which can obtain uniform illuminance over a wide region to incident light having a large wavelength band such as white light and can provide a high quality picture without lowering a contrast.

In the picture display device having a reflection type display part, a light transmission plate in which a diffraction grating is formed on one surface and a front light optical system including a light transmission plate, the diffraction conditions of a light transmission plate can be set so that diffraction efficiency is high to incident light and the diffraction efficiency is low to light from a reflection type display part by forming a first transparent layer having a refractive index different from that of a light transmission plate along the diffraction grating. That is, the lowering of the contrast is prevented. Illuminating light is efficiently transmitted to the reflection type display part, and a picture with high uniformity is provided over the whole area of a wavelength band.