A method of manufacturing a functional film by which the functional film formed on a film formation substrate can be easily peeled from the film formation substrate. The method includes the steps of: (a) forming a separation layer by using an inorganic material on a substrate containing a material having heat tolerance to a predetermined temperature; (b) forming a layer to be peeled containing a functional film, which is formed by using a functional material, on the separation layer; and (c) performing heat treatment on a structure containing the substrate, the separation layer and the layer to be peeled at the predetermined temperature so as to peel the layer to be peeled from the substrate or reducing bonding strength between the layer to be peeled and the substrate.