An STN liquid crystal display device includes a polarizer and an analyzer which are arranged to sandwich an STN liquid crystal cell, and two biaxial retardation plates arranged between a substrate of the liquid crystal cell and the analyzer. The polarizer is arranged such that its light-transmitting axis is inclined at about 140.degree. with respect to an incident-side aligning treatment direction of the liquid crystal cell. The analyzer is arranged such that its light-transmitting axis is inclined at about 55.degree. with respect to the incident-side aligning treatment direction. The biaxial retardation plate on the liquid crystal cell side is arranged such that its phase delay axis is inclined at about 40.degree. with respect to the incident-side aligning treatment direction. The biaxial retardation plate on the analyzer side is arranged such that its phase delay axis is inclined at about 5.degree. with respect to the incident-side aligning treatment direction. Each biaxial retardation plate has a refractive index n.sub.X in the extending direction of the retardation plate, a refractive index n.sub.Y in the direction perpendicular to the extending direction, and a refractive index n.sub.Z in the direction of thickness, which satisfy n.sub.Y