Abstract: A twisted nematic liquid crystal display device employing a nematic liquid crystal material having positive dielectric anisotropy comprises a twisted nematic liquid crystal cell sandwiched between a pair of transparent substrates coated on the inside surface thereof with a conductive layer, and a pair of linear polarizers disposed adjacent the substrates. At least one of the linear polarizers can be changed in its orientation by 90.degree. about the optical axis of the liquid crystal cell and is made demountable so as to be replaceable with another linear polarizer.