Abstract: Proposed is a novel casing for frame-supported pellicle used for dustproof protection of a photomask in the photolithographic patterning process for the manufacture of fine electronic devices. Different from conventional casings made from a plastic resin, the casing of the invention is characterized by the use of a unique permanently antistatic resin composition which is a resin blend consisting of 80-95% by weight of an ABS or acrylic resin and 20-5% by weight of a specific hydrophilic polymer. By virtue of the excellent antistatic behavior of the resin composition, the frame-supported pellicle encased in the casing is safe from the troubles due to deposition of dust particles during transportation and from contamination by the vaporized matter from the casing.