A flat panel display device which is capable of preventing in-line shorts by forming as a face plate a common power line impressing an equal power supply to all pixels. The flat panel display includes a power supply layer formed on an insulation substrate and connected with source/drain electrodes through contact holes; and an insulating layer formed with a contact hole to insulate the power supply layer and a thin film transistor, wherein the thin film transistor is formed over the insulating layer and includes the source/drain electrodes.