The present invention relates to an optical modulation device that maintains good contrast despite changes in temperature and is capable of performing stable display. A polarizer, a first and second modulator and an analyzer are provided. Each modulator is a chiral smectic liquid crystal layer held between two opposite substrates which have different orientation determining abilities. The chiral smectic liquid crystal layers have at least two stable alignment states and substantially the same temperature dependency and tilt angle. The molecular axis of the first modulator at one of the two stable alignment states is substantially parallel to a transmitting modulation axis of said polarizer and is substantially perpendicular to a transmitting polarizing axis of said analyzer, and a molecular axis at one of the two stable alignment states of said second modulator is substantially parallel to a transmitting polarization axis of said analyzer.