To obtain an unsealing tape excellent in mechanical strength in the longitudinal direction, constant in dimensional change on heating, hardly causing shrinkage wrinkles and excellent in appearance by adhering a hot melt adhesive to a specific blaxially oriented polypropylene film and subsequently slitting the film in a desired width.

This unsealing tape is obtained by subjecting a polypropylene (PP) sheet having a melt index of 0.5-5g/10min to the first stretching treatment into a length of 4-5.5 times in the longitudinal direction at 140-150°C by a tenter method, subjecting the sheet to the second stretching treatment into a total length of 6.5-7.5 times in the same longitudinal direction at 145-155°C higher than the temperature of the first stretching treatment, further stretching the sheet into a length of 6-10 times in the latitudinal direction at 150-180°C, adhering (thickness: preferably 1-100μm) a hot melt adhesive such as ethylene-vinyl acetate copolymer adhesive to the biaxially stretched PP film having a tensile breakage strength of ≥18kg/mm2 in the longitudinal direction and a thermal shrinkage of 1-5% at 120°C in the longitudinal direction, and subsequently slitting the film in a desired width.