Provided are a photomask and a method of correcting errors thereof. The photomask includes a multilayer reflection film covering one side surface of a substrate and an energy receiving layer covering the other side surface of the substrate. The method includes determining a local correction position on a frontside surface of the photomask according to a detected error of the photomask, and locally applying an energy beam to a backside surface region of the photomask aligned with the local correction position in a thickness direction of the photomask. The invention may be applicable to structures other than photomasks that benefit from modification of surface heights or selectively applied stress.