In an IPS mode LCD device and method, a plurality of sub-blocks are utilized to maintain a maximum transmittance even when a voltage above a predetermined value is applied to the device. The IPS mode LCD device includes a common electrode including a plurality of first segments and a plurality of second segments to define a plurality of blocks, wherein the plurality of first segments are formed substantially parallel to the gate line in the pixel region, and the plurality of second segments are formed substantially parallel to the data line, and connected to the first segments; and a pixel electrode including a plurality of third segments and at least one fourth segment, and being connected with a drain electrode of the thin film transistor, wherein each of the third segments is positioned between the first segments, and the at least one fourth segment connects the third segments.