The present invention provides a liquid-crystal display device capable of maintaining a high voltage holding ratio even without an alignment film. The liquid-crystal display device of the present invention includes a pair of substrates, a liquid crystal layer which is sandwiched between the substrates and which contains a liquid crystal material, and a polymer layer which is disposed on a surface of each of the substrates and which controls the alignment of liquid crystal molecules. The outermost surfaces of both the substrates comprise substantially no alignment film. The polymer layer is formed by polymerizing one or more radical polymerizable monomer species added to the liquid crystal layer. At least one species of the one or more radical polymerizable monomer species is a biphenyl compound having a specific structure.