A protective film for an electronic device is introduced. The protective film may comprises a deformable outer layer formed with a synthetic resin; a deformable modified material layer attached with a lower surface of the deformable outer layer, wherein the deformable modified layer is configured to be hardened responsive to receipt of an external stimuli; a deformable inner layer formed with a synthetic resin, attached with a lower surface of the deformable modified material layer; and an adhesive layer adhering to a lower surface of the deformable inner layer. Further, various embodiments can be implemented according to the present disclosure.