PURPOSE: To obtain a new ferroelectric liquid crystalline compound, excellent in thermal stability, having great spontaneous polarization and most suitable for producing a liquid crystal device having a high speed of response and having an optically active group and cyclic sulfone group.

CONSTITUTION: A ferroelectric liquid crystalline compound having an optically active group such as an alkyl, an alkyloxy or an alkyl halide and a cyclic sulfone group such as dioxothiazolidione ring, e.g. a compound expressed by formula I or II. Furthermore, a new ferroelectric liquid crystal composition 7 containing at least one of this ferroelectric liquid crystalline compound is used in a liquid crystal display device having, e.g. polarizing plates 1, substrates 2, transparent electrode films 3, oriented films 4, a sealing material 5 and spacers 6. This ferroelectric liquid crystal has an ultrahigh speed of response due to spontaneous polarization and further is capable of developing a bistable state with memory properties. Visibility angle characteristics are excellent and the ferroelectric liquid crystal is suitable as a high-capacity and large-screen display.