The purpose of the present invention is to provide an image display device capable of preventing the creation of stray light due to external light, improving the visibility for a user, and reducing the size of an optical system. The image display device according to the present invention comprises: a light source (1) for emitting light; a display element (3) for generating display light by receiving light from the light source; a light guide plate (5) for propagating the display light therethrough; an incidence element (4) for introducing the display light from the display element into the light guide plate; and a dynamic light-emitting diffraction grating (6) provided in the light guide plate for emitting the display light outside the light guide plate. The dynamic light-emitting diffraction grating (6) includes a plurality of divided dynamic diffraction grating elements in which light diffracting function is enabled or disabled in accordance with the application of a voltage. The image display device further includes a control unit for controlling the dynamic light-emitting diffraction grating so that the plurality of divided dynamic diffraction elements may only be enabled with the light diffracting function one at a time.