The purpose of the present invention is to simply and reliably cut off the remainder of a sheet present on an opening of a cup having a certain volume, when the cup is moulded from the sheet. A method for producing a cup according to the present invention is provided with: a moulding step in which a cup having a certain volume is moulded from a sheet； and a processing step in which a part of the circumferential wall of the cup, said part protruding from the remainder of the sheet, is irradiated with a laser beam from a direction intersecting the circumferential wall, in order to cut the remainder of the sheet from the cup.［課題］在從薄片來形成具有容積之封杯時，簡便且確實將該當封杯的開口部上所存留之薄片的殘部予以切除。 ［解決手段］本發明所述之封杯的製造方法，係具備：成形工程，係從薄片來形成具有容積之封杯；和加工工程，係為了從前記封杯切除前記薄片的殘部，而在從薄片的殘部所突出之封杯的周壁的部位，從對該當周壁呈交叉之方向，照射雷射光。
