An image display device includes: an image forming device; an optical device having a virtual image forming region where a virtual image is formed on the basis of light emitted from the image forming device; and a dimming device for adjusting the amount of external light incident from the outside, disposed so as to face the virtual image forming region and to be away from the optical device. The dimming device includes: a transparent protective substrate on which external light is incident; a dimming layer formed on a surface of the protective substrate facing the optical device; and a moisture-retaining layer formed on the dimming layer.