An area light source device, which is disposed between a liquid crystal
display panel and a display medium and illuminates the liquid crystal
display panel from a back side thereof, includes a light source, a light
guide, and a first optical sheet and a second optical sheet which are
stacked between the liquid crystal display panel and the light guide and
impart predetermined optical characteristics to emission light emerging
from the light guide. The first optical sheet is disposed on the liquid
crystal display panel side, and the second optical sheet is disposed on
the light guide side. The first optical sheet and the second optical
sheet have opening parts opposed to the display medium, and the first
optical sheet is disposed to cover edges that define the opening part of
the second optical sheet.