The present invention provides, at low cost, a self-supporting
package which is excellent in
heat resistance and can be sterilized at high temperatures and the content of which is drunk through a
straw. That is, the present invention provides a self-supporting bag which comprises front and back materials consisting of a
composite film having a seal layer and having flexibility, and a bottom material consisting of said
composite film and folded in the form of the letter W between the front material and the back material, wherein a
straw-thrusting film consisting of said
composite film is folded in the form of the letter M between the front material and the back material in inverse direction to the bottom material and provided from one side seal to the other side seal of the self-supporting bag, the
straw-thrusting film being heat-welded to either one of the front material and the back material, and further provides a self-supporting
package comprising said self-supporting bag which is charged with a content and closed by sealing, wherein a seal part is provided in the upper portion of the bag, said seal part having an unsealed part having a width of 2 mm or more in longitudinal direction including therein the upper edge of the straw-thrusting film and a width in lateral direction within the width of the self-supporting bag.