Disclosed is a novel liquid-crystalline compound which is a naphthalene derivative useful as an electro-optical liquid crystal display material, a liquid crystal composition containing such naphthalene derivatives and a liquid crystal display device comprising the same. The naphthalene derivative provided by the present invention exhibits an excellent liquid-crystallinity and miscibility with currently widely used liquid crystal compositions or compositions. The addition of the naphthalene derivative makes it possible to drastically lower the threshold voltage of the liquid crystal composition while maintaining its high response. The naphthalene derivative of the present invention is characterized by a large birefringence index. Further, most of the naphthalene derivative of the present invention has no strongly polar group in its molecule and thus can also be used for active matrix driving. Moreover, as shown in the foregoing examples, the naphthalene derivative of the present invention can be easily produced and is colorless and chemically stable. Accordingly, the liquid crystal composition comprising the naphthalene derivative of the present invention is extremely useful as a practical liquid crystal composition, particularly a liquid crystal composition which can operate within a wide temperature range and requires a high speed response and a low voltage driving.