An optically liquid crystalline compound having an extremely large spontaneous polarization value and a chiral smectic liquid crystal composition containing the compound are provided, the compound being expressed by the formula ##STR1## wherein m represents an integer of 2 to 18; l represents an integer of 0 to 12; n represents 0 or 1; R represents an alkyl group or an alkoxy group each of 2 to 20 carbon atoms, a halogen atom or cyano group; and A and B each represent a single bond, ##STR2## wherein X represents hydrogen atom, a halogen atom or cyano group, and a chiral smectic liquid crystal composition containing at least one kind of the above compound.