It is an object of the invention to provide a method for producing a combined optical film that includes opposing the end faces of a plurality of optical films to one another and can narrow the gap between the opposed end faces. A method for producing a combined optical film comprising a plurality of optical films each having at least one end face at which the optical films are opposed to one another, comprising the steps of: (1) opposing the end faces of the optical films to one another with a gap provided therebetween; (2) bonding a first seal material to the opposed portions of the optical films on a first side of each optical film to join the optical films; (3) bending the joined opposed portions of the optical films such that the joined opposed portions become concave on a second side of each optical film where the first seal material is not bonded and such that the gap is narrowed on the second side; (4) bonding a second seal material to the opposed portions on the second side, while the joined optical films are bent such that the gap is narrowed on the second side; and (5) cancelling the bending of the joined optical films to make them flat.