A method of manufacturing an LCD device is disclosed. The LCD device manufacturing method includes: forming first and second active patterns on P-channel and N-channel thin film transistor formation regions of a substrate using a first masking process, respectively; forming a first gate electrode on the P-channel thin film transistor formation region of the substrate using a second masking process; forming a second gate electrode on the N-channel thin film transistor formation region of the substrate using a third masking process; forming first contact holes partially exposing the respective N and P source regions and second contact holes partially exposing the respective N and P drain regions, using a fourth masking process; forming N and P source electrodes connected to the N and P source regions, and N and P drain electrodes connected to the N and P drain regions, using a fifth masking process; simultaneously forming third contact holes and a common electrode using a sixth masking process; forming fourth contact holes, which expose the respective N and P drain electrodes, using a seventh masking process; and forming a pixel electrode using a eighth masking process.