A method of manufacturing a flexible display device and a carrier substrate for manufacturing the same are disclosed. In one aspect, the method includes preparing a first release area and a first attachment area around the first surface area on a first surface, attaching a base substrate to the first surface, and forming a display unit on the base substrate corresponding to the first release area of the carrier substrate. The method also includes cutting the area of the base substrate corresponding to the first release area of the carrier substrate so as to include the display unit, and separating the cut base substrate from the carrier substrate. Thus, the carrier substrate and the base substrate may be smoothly combined with each other and separated from each other without an additional mask deposition process. Also, damage to a product that may occur during combination and separation of the substrates may be much reduced.