An improvement is proposed for a frame-supported pellicle used for dust-proof protection of a photomask in the photolithographic patterning work in the manufacture of semiconductor devices. In view of the problem that, when a frame-supported pellicle having the other end surface of the frame coated with a pressure-sensitive adhesive and temporarily protected by attaching a releasable protective sheet of a plastic resin prepared by die punching is handled or transported as packaged, subsequent occurrence of dust particles is more or less unavoidable from the rugged die-punched sections, the die-punched peripheries of the protective sheet is subjected to a smoothening treatment by locally dissolving with an organic solvent, by locally melting at a temperature higher than the melting point of the plastic resin or by coating with a coating composition so that the protective sheet is absolutely not responsible for the subsequent formation of dust particles.