Packaging bag using polybutylene terephthalate film

A packaging bag comprising a laminated body in which a gas barrier film, a polyolefin film sealant layer, and a biaxially stretched polyethylene terephthalate film are laminated,

• wherein the gas barrier film is obtained by sequentially laminating a biaxially stretched polybutylene terephthalate film, an adhesion layer, an inorganic thin film layer, and a protective layer,
• wherein the biaxially stretched polyethylene terephthalate film is laminated on a surface of the biaxially stretched polybutylene terephthalate film opposite to the polyolefin film sealant layer side of the biaxially stretched polybutylene terephthalate film,
• wherein the biaxially stretched polybutylene terephthalate film has a thickness of 8 to 25 μm, the polyolefin film sealant layer has a thickness of 10 to 100 μm, and the protective layer comprises a urethane-based resin, and
• wherein the biaxially stretched polybutylene terephthalate film satisfies (a) to (c) below:
• (a) the biaxially stretched polybutylene terephthalate film contains 60% by mass or more of a polybutylene terephthalate resin;
• (b) a thermal shrinkage of the biaxially stretched polybutylene terephthalate film after heating at 150° C. for 30 minutes is −2 to +4% in both the machine direction and the transverse direction;
• and
• (c) a total amount of 1,4-butanediol and tetrahydrofuran volatilized during heating at a temperature of 135° C. for 60 minutes is 2000 ppb or less.