Provided are a method of separating a metal layer and an organic light emitting diode. A method of manufacturing a flexible device and a method of manufacturing a flexible display include forming a releasing layer on a substrate, forming a metal layer on the releasing layer, forming an insulating layer on the metal layer, forming a releasable layer on the insulating layer, bonding a plastic to the releasable layer, and separating the substrate and the releasing layer at an interface therebetween to manufacture a flexible device. Since the conventional process equipment using the glass substrate can be compatibly used, the manufacturing cost can be reduced. In addition, since the glass substrate has less limitation in the process temperature compared with the plastic substrate, an electric device having a superior performance can be manufactured. Furthermore, the glass substrate has good thermal/chemical stability and is less deformed compared with the plastic substrate, whereby process control such as substrate alignment becomes easy.