This invention relates to an apparatus and method for cleaning a photomask. This apparatus, suitable for use in removing an adhesive residue from a photomask, includes a photomask disposed such that a surface thereof on which an adhesive residue is left behind is directed downwards, a metal plate formed adjacent to the adhesive residue, and a laser generator for irradiating a laser onto the metal plate so that the adhesive residue is removed by heat generated from the metal plate.