An optical prism 100 for reflecting light incident on its light incidence surface 12 suited for incidence of light from an LCD 20 at least twice within itself and emitting the reflected light as emitted light from a light emission surface 14 to the outside. The optical prism is coupled in use with a display element support 30 adapted to suit it. The side surfaces of the optical prism crossing the light incidence surface 12 and light emission surface 14 have projections 90L and 90R for mounting the optical prism on the display element support.