PURPOSE: To stably and easily produce a liquid crystal medium by densely filling a liquid crystal phase with solid particles.

CONSTITUTION: The medium consists of a liquid crystal phase and solid particles which densely fill the liquid crystal phase. The ratio Q of the volume replaced by the particles to the specific volume of the solid ranges from 0.005 to 0.15, and the particles can be moved by external influences. A highly effective light- scattering layer of the medium changes into transparent by an electric field and can maintain its high transparency after the switch is turned off. Moreover, the layer generates light-scattering property by mechanical force, irradiation of electromagnetic waves or temp. increase and cooling. This scattering property can be returned into transmitting property by an electric field. The medium particles consist of an inorg. material which can contain an org. material in the surface layer, and are preferably oxides of silicon, aluminum and titanium, and especially, particles of calcined silica or its deriv. are preferable.