Spouted packaging bag and method for producing spouted packaging bag

A spouted packaging bag comprising:

• a storage portion made of laminated films each having a base material and a sealant layer that are made of the same material;
• and
• a spout having a spout tube extending in a first direction and a base provided on one end side of the spout tube, the spout being attached to an edge portion of the storage portion,
• wherein the sealant layer is welded to the base of the spout and the sealant layers are welded to each other at a side of the base at the edge portion of the storage portion,
• wherein a width of a first welding region where the sealant layer is welded to the base, along the first direction, is shorter than a width of a second welding region where the sealant layers are welded to each other, along the first direction, and a step is formed between the first welding region and the second welding region.