An IPS (in-plane switching mode) liquid crystal display device and fabricating method thereof, in which post treatment lowering the pre-tilt angle is performed on a rubbed alignment layer on a substrate using a non-rubbing method such as UV or ion-beam irradiation, and by which a viewing angle characteristic is enhanced. The present invention includes a first substrate, a second substrate, a gate line and a data line crossing with each other on the first substrate to define a pixel area, a thin film transistor at a crossing of the gate and data lines, a pixel electrode and a common electrode alternately arranged in the pixel area a predetermined interval from each other, an alignment layer over the pixel and common electrodes having a pre-tilt angle equal to or smaller than about 1.degree., and a liquid crystal layer between the first and second substrates.