<；P>；PROBLEM TO BE SOLVED: To provide a polymer packaging bag which has satisfactory sealability and sufficient strength to package heavy stuff. <；P>；SOLUTION: The packaging bag is a bag made of a polymer film, packaging a heavy stuff of 300 g or more. The thickness of the polymer film is 10 to 200 &mu；m. The packaging bag is formed by folding back the polymer film so as to form the bottom, then forming heat seals with a width of 2 to 15 mm along the side edges of the bags and further forming weld seals along the side edges thereof. In the bag, the strength of the bottom and the average seal strength of the side edges are 15 N/15 mm or more. <；P>；COPYRIGHT: (C)2007,JPO&INPIT
