An image display device including a transparent panel and a display adjustment layer is provided. The transparent panel displays a superimposed image corresponding to a surface region at a first region. The display adjustment layer is on the transparent panel for reserving a monocular vision to see the superimposed image. When a first eye and a second eye see the surface region through the image display device, the first eye sees the superimposed image superimposed on the surface region but the second eye only sees the surface region.