PROBLEM TO BE SOLVED: To provide a package where the holding of a derivation tool is sufficiently achieved and a content is hardly leaked from between the derivation tool and the package in the package mounted with the derivation tool after opening.SOLUTION: In a package 100, the facing inner surfaces of a packaging material are joined together at least at a part of the outer periphery of the package and then an encapsulation part 101 encapsulated with a content is formed. The encapsulation part 101 has an extension part 102 projected locally toward the marginal part of the packaging material. The package 100 is opened by cutting the packaging material at a position traversing the extension part 102. A straw 150 is inserted from an opened port formed by cutting. The extension part 102 is formed with a dimension applied with tension in a circumferential direction of the straw 150 to the packaging material when the straw 150 is inserted.
