PURPOSE: To make it easy to break the seal in unwrapping a rectangular object wound in packing film on fox sides perimetrically, by making two incisions in the fringe of the opening formed by the packing film which projects from an unwrapped side, one incision on each side of the joint of the packing film at the fringe, to form an unsealing tab.

CONSTITUTION: In packing an object 1 such as a tape cassette, an unsealing tab 5 is formed by making two incisions 4a, 4b in the fringe 2b of the opening formed by a sheet of packing film 2 wound on the object 1 on four sides perimetrically, one incision on each side of the joint 2a of the fringe 2b. When the fringe 2b projecting from the unwrapped side of the object 1 is tucked down on the end side of the object 1, the unsealing tab 5 is brought to be exposed and, when the fringe 2b tucked on the end side is heat-sealed, the unsealing tab 5 is left loose. To break the seal, the unsealing tab 5 is pulled; since the joint 2a is formed thicker than the rest of the film, the unsealing is orientated and the packing film 2 is torn off along the joint 2a from top to bottom and severed.