A polybutylene terephthalate resin having 30 eq/t or less of carboxyl end group, a crystallization temperature in a temperature decrease of 175° C. or higher and an amount of residual tetrahydrofuran of 300 ppm by weight or less; and compositions and molded articles comprising the resin and glass fiber, antioxidants and mold-releasing agents is provided. The polybutylene terephthalate resin can be molded in a short molding cycle, exhibits excellent resistance to hydrolysis and mold-releasing property, causes no corrosion of metals and generates little gas during molding. The compositions and the molded articles exhibit improved impact resistance, stability under heating and oxidation and mold-releasing property and can be advantageously used for members in electric and electronic products and in automobiles.