A pad layout structure of a driver IC chip of a liquid crystal display device includes dummy power pads and dummy ground pads, which are disposed in corners of the driver IC chip and are connected to main power pads and main ground pads by metal lines in a chip-on-film (COF) package. Accordingly, it is possible to reduce the resistance of power supply lines and ground lines, to minimize a power dip of a block located far away from the main power pads and main ground pads, and to prevent a failure in power application, which may occur due to a decrease of adhesive strength at a specific position, by dispersing the adhesion positions of the power pads and ground pads.