An in-plane switching mode liquid crystal display device includes: first and second substrates facing and spaced apart from each other; a first polarizing plate including a supporting layer, a first polarizing layer and a first protecting layer sequentially on an outer surface of the first substrate; a second polarizing plate including a first compensating layer, a second compensating layer, a second polarizing layer and a second protecting layer sequentially on an outer surface of the second substrate, the first and second compensating layers including positive and negative biaxial retardation films, respectively; and a liquid crystal layer between the first and second substrates.