the above general formula 1 in which y is a hydrogen atom or desirably an optically active compound of the above general formula 1 in which n is an integer of 3 to 8 it is also desirably an optically active compound of the general formula 1 in which x is a single bond u2014 or u2014 ooc u2014 further the optically active compound of the present invention is preferably an optically active compound of the above general formula 1 in which a is ph and it is also preferably an optically active compound of the above general formula 1 in which b is ph z cy di u2014 o u2014 or ph cy the optically active compound of the present invention desirably has a helical twisting power htp of 50 or more the optically active compound of the present invention is suitably used as a chiral dopant for a nematic liquid crystal and is suitably used in the form of a nematic liquid crystal composition containing at least one compound of the general formula 1 and the nematic liquid crystal composition is advantageously used in a liquid crystal display device to be interposed between substrates having electrodes the optically active compound of the present invention includes an r configuration compound and an s configuration compound and any one of these can be suitably used that is the r configuration compound and the s configuration compound differ from each other in twisting direction right handed twisting or left handed twisting of the helical structure induced these compounds are therefore selected by taking account of the twisting direction of a chiral dopant to be used in combination the optically active compound of the present invention has excellent compatibility with a.