Abstract: In a bag 10 for packaging having a first face 10A and a second face 10B that are mutually opposite, a first line of weakness 100A (100B) and a second line of weakness 200A (200B) and a third line of weakness 300A (300B) constituted by a plurality of breaks of perforation form arranged between the first line of weakness and the second line of weakness and having an inclination with respect to a prescribed unsealing direction L50 are respectively formed in the first face and the second face such that these are arranged in mutually parallel fashion, and the plurality of breaks of perforation form constituting the third line of weakness formed in the first face and the plurality of breaks of perforation form constituting the third line of weakness formed in the second face are formed inclined in mutually opposite directions with respect to the prescribed unsealing direction. In this way a finger-grip portion of suitable extent is formed at the unsealed aperture of the bag for packaging after unsealing.