An in-plane switching liquid crystal display device includes a first substrate, a second substrate spaced apart from the first substrate, a liquid crystal layer between the first and second substrates, a first polarizer at an outer surface of the first substrate, the first polarizer including a first polarization film and first inner and outer supporting film at both sides of the first polarization film, the first inner supporting film adjacent to the first substrate and having a retardation within a range of about -10 nm to about +10 nm, and a second polarizer at an outer surface of the second substrate, the second polarizer including a second polarization film and second inner and outer supporting film at both sides of the second polarization film, the second inner supporting film adjacent to the second substrate.