An optical sheet includes a light scattering layer which scatters light
made incident from an incident surface to an emission surface side and a
plurality of light reflecting portions which reflect light scattered by
the light scattering layer to the light scattering layer side. The
optical sheet further includes a plurality of light transmitting portions
constituted of an air layer for transmitting the scattered light to
lenticular sheets. The plurality of the light transmitting portions are
arranged along a longitudinal direction so as to form a convex portion
with respect to a non-lens surface. Consequently, the light reflecting
portions and the light transmitting portions are disposed alternately in
stripes along an arrangement direction.