A display device includes: a frame to be mounted on a head of an observer; and an image display device attached to the frame. The image display device includes: an image forming device; a light guide plate; a support substrate; a first deflection unit; a second deflection unit; and an optical member attached to the support substrate, in which light from the image forming device is deflected at the first deflection unit, propagated inside the light guide plate by total reflection, deflected at the second deflection unit, and incident on the optical member, and the optical member emits the incident light toward a pupil of an observer. The display device further includes a movement device that moves the support substrate with respect to the light guide plate in order to change a relative positional relation between the second deflection unit and the optical member.