Namely, a polymer such as polyvinyl chloride and polycarbonate is dissolved in a solvent in which also is dissolved liquid crystal such as N-(4-ethoxybenzylidene)-4'-butyl aniline, butyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate or the like, and the thus prepared solution is spread in a petri dish so as to allow the solvent to evaporate, whereby a film is formed.