A liquid crystal composition containing an optically active or a ferroelectric liquid crystal compound represented by the following formula: ##STR1## wherein: A is selected from the group consisting of oxygen and sulfur; B is selected from the group consisting of --(CH.sub.2).sub.m -- and --(CH.sub.2).sub.n --O--; R is an alkyl or alkoxyl group having 1 to 22 carbons; R' is an alkyl group having 2 to 8 carbons or an ether group having 2 to 8 carbons; m is an integer from 0 to 4; n is an integer from 2 to 5; k is an integer of 0 or 1; l is an integer of 0 or 1; C and D are selected form the group consisting of hydrogen atom and halogen atoms, and * represents a chiral center. The ferroelectric liquid crystals of the present invention exhibit optical and chemical stabilities, high-speed switching characteristic and high spontaneous polarization, and thus are excellent materials for use in liquid crystal devices and liquid crystal light switching elements.