Abstract: The invention is a polyester resin mainly comprising a terephthalic acid component and a glycol component, wherein the fluorescence spectrum obtained by irradiating the polyester resin with excited light having a wavelength of 343 nm has a fluorescence intensity at 450 nm (B0) of 20 or lower. The resin makes it possible to efficiently produce a shaped article, especially a heat-resistant blow-molded article, that has excellent transparency and a moderate and stable crystallization rate and excellent heat-resistance dimensional stability, and is prevented from emitting fluorescence when irradiated with UV rays, and which is excellent in long-run continuous workability with no mold contamination, and which provides a wrapping material having excellent flavor retentiveness.

Abstract: The present invention relates to a polyester composition excellent in transparency, thermal stability, and flavor retention or excellent in transparency, thermal stability, flavor retention and gas barrier properties, which is obtained by blending a partially aromatic polyamide to a thermoplastic polyester, and also relates to a packaging material comprising the same. The polyester composition of the invention preferably contains an alkali metal atom in an amount of 0.1 to 300 ppm and phosphorus atom in an amount of 5 to 200 ppm. Further, it is preferable that the Color-L value of the molded article obtained by injection molding of the polyester composition of the invention at a molding temperature of 290° C. is 80.0 or more and the haze thereof is 20% or less. As the partially aromatic polyamide, an m-xylylene group-containing polyamide is preferable.