To provide a bag which offers improved operability in pouring out contents, and improved spout openability.

According to the bag 10, the lower edge of a gusset folded part 14A, which is determined to be one side of the gusset folded part 14A formed on a top sheet 14, is joined to the upper edge of a first trunk sheet 11 via an intermediate sealing part 24. An upper angled portion formed between a side sealing part 22B and a top sealing part 25 serves as a spout forming portion 30. An inflection point A is formed at or near the spot where the extension line of the spout axis 31 of the spout forming portion 30 crosses the intermediate sealing part 24.