A liquid crystal display device of IPS mode includes an array of pixels arranged in a matrix pattern by crossing a plurality of video signal lines and a plurality of scanning signal lines each other. Each of the pixels is provided with at least a switching element. A transparent insulating film is provided on both signal lines, and a plurality of pixel electrodes, common electrodes and common lines are provided on the transparent insulating film. The common lines are formed in a grid-shaped pattern such that a first group of the common lines is made of a first conductor having lower reflectivity against optical light than that of metal while a second group of the common lines is made of a second conductor including a metal layer such that said first group and said second group are crossing each other along said video signal lines and said scanning signal lines.