PURPOSE: To prevent a pilot from feeling a shift in the position of an image and variation in the size of the image by arraying two half-mirrors in front of the pilot so that two virtual images are coincident in a relative position relation.

CONSTITUTION: Various displays 1 of the flying direction, etc., of an aircraft are produced on a CRT, etc.; and virtual images 9 and 12 are formed on a screen 8 at a finite-distance point through half-mirrors 5 and 11 which slant at a specific angle relatively and the video of an external field is projected from the reverse surface of the screen 8. The two images are coincident in center even when the pilot sees the virtual image 9 of the displays 1 with the eye at a position 7 and sees the virtual image 12 with the eye slightly above. Those tow mirrors are used, so the visual field is expanded and there is variation in neither the display position nor size even when the position of the eye is changed; and the pilot feels no fatigue in the eye even when the display is applied to a dome type simulator.