A method of producing a flat panel display including step 1-step 4, or step 1-step 5, where at least one of the optical elements after step 4 or step 5 can be reused as an optical element in step 1: step 1: adhering two optical elements to each other via an adhesive sheet or a curable resin layer, and applying an autoclave treatment to give an optical laminate step 2: checking the appearance of the optical laminate obtained in step 1 step 3: assembling a flat panel display using the optical laminate that passed the check in step 2 step 4: separating the two optical elements in an optical laminate that was rejected by the check in step 2 by relatively rotating them with a vertical line penetrating the opposing faces thereof as a rotation axis step 5: washing the optical element resulting from step 4.