A method of manufacturing a flexible display device, includes forming a base layer on a non-flexible substrate, the base layer including a first resin layer, an inorganic film, and a second resin layer, wherein the forming of the base layer includes a first step of forming the first resin layer inward from an end portion region of the non-flexible substrate, a second step of forming the inorganic film on the first resin layer such that the non-flexible substrate and/or the first resin layer is exposed, and a third step of forming the second resin layer in contact with the non-flexible substrate exposed from the inorganic film and/or the first resin layer exposed from the inorganic film, and the method further includes peeling the non-flexible substrate and bonding a flexible substrate to the first resin layer via an adhesive layer.