An information display device has an information display plate where at
least one or more kinds of particles are sealed between cells formed by a
partition wall, the cells being between two opposite substrates at least
either of which is transparent. At least either of electrodes is provided
on a substrate, and an electric field is applied to the particles by the
electrodes to move the particles, causing information such as an image to
be displayed on the display plate. The surfaces of the substrates are
smoothed by making D.gtoreq.2H satisfied, with D being the diameter of a
particle (a particle forming the particles), H the height of the
electrodes. This thins the electrodes as much as possible (making the
height of the electrodes small) and smoothes the surfaces of the
substrates, and as a result, the information display device after an
endurance test has an improved contrast ratio.