To enable both an easy-to-open property and an anti-bag breakage property to be satisfied although a package is manufactured by a pillow packaging machine.

A package 1 is manufactured by using a pillow packaging machine. Some stored items are filled in a three-side seal bag made of film having a vertical seal segment 2, an upper lateral seal segment 3, and a lower lateral seal segment 4. The vertical seal segment 2 and the lower lateral seal segment 4 have such a melting and adhering strength as one not to cause themselves to be peeled off under a usual used state of the bag. To the contrary, the upper lateral seal segment 3 has a melting and adhering strength of easy-to- open property, so that the upper lateral seal segment 3 is peeled off to easily open and it shows a superior resistance to breakage of bag.