A polyethylene terephthalate resin composition suitable for use in moldings which comprises:(A) 5 to 93 parts of a polyethylene terephthalate resin and(B) 95 to 7 parts of a polyethylene terephthalate block copolymer having 10 to 55% by weight of units represented by the formula (I): ##STR1## wherein R.sup.1 and R.sub.2 are the same or different and each is a bivalent hydrocarbon group having 2 to 4 carbon atoms, R.sup.3 to R.sup.10 are the same or different and each is hydrogen atom, a monovalent hydrocarbon group or a halogen atom, X is a bivalent group or single bond, and each of m and n is an integer of 5 to 20, said parts of said components (A) and (B) being parts by weight based on the total amount of said components (A) and (B). The composition of the invention can be molded according to injection molding as well as extrusion, and the obtained molded articles have the excellent heat resistance, surface property and fatigue resistance.