To provide a head mount type image display device which is lightweight, small-sized, and inexpensive and can perform display with a wide angle of view.

The head mount type image display device has one image display element and a display optical system for left and right eyes. The display optical system consists of optical element groups which guide a luminous flux including an image displayed on the image display element to right and left eyeballs of an observer and are arranged in nearly mirror-symmetrical positions and have the nearly same shapes, and has at least one reflecting surface. The luminous fluxes from left and right pupils of eyeballs of the observer are reflected by the first reflecting surface of backward beam tracing from left and right pupils of eyeball, in such directions that the luminous fluxes go away from each other.