An object of the invention is to provide a surface illumination device and a display device using it, which can contribute to improvement of display qualities. A surface illumination device comprising a light guide plate 1 for propagating incident light inside itself and reflecting the light at the reflecting prism face 1S to output the light from the light exit face. This further comprises: a polarizing plate provided on the light exit face; and an anti-reflection film 4 provided on the polarizing plate. The reflecting prism face 1S extends so that a direction of electric vector's vibration of an s-polarized light component of a reflecting light ray caused by an incident light ray in a predetermined propagation direction is in parallel with a polarization axis of the polarizing plate, whereby a light efficiency can be improved. |