When materials of a cathode and an anode are transparent and a substrate
with transparency is used for a substrate and a sealing substrate,
luminescence from a layer including an organic compound can
simultaneously perform two ways of display: luminescence passing a
cathode and luminescence transmitted in an anode. However, interference
effect by an optical distance difference results in difference in optical
characteristics (such as a color tone) between luminescence from a top
surface and luminescence from a bottom surface. According to the present
invention, a light-emitting device having luminescence from a top surface
and luminescence from a bottom surface provides both luminescence to a
top surface and luminescence to a bottom surface with an image display
having an uniform color tone and of high quality by regulating a film
thickness of a transparent conductive film disposed on a cathode side and
a film thickness of a cathode.