An image display device includes: a display part, a measuring instrument, a determination unit, a detection unit, a decision unit, and a notification processing unit. The display part allows a user to visually recognize a display image by projecting an image light corresponding to the display image on an eye of the user in a state where some ambient light reaches at least either one of eyes of the user. The measuring instrument measures brightness of the ambient light. The determination unit determines brightness of the display image. The detection unit detects the difference between the brightness of the ambient light and the brightness of the display image. The decision unit decides timing of temporarily stopping the use of the display part. The notification processing unit performs notification which prompts the user to stop the use of the display part at the timing.