PURPOSE: To obtain a resin composition having improved balance of tensile strength and elongation and few burrs, containing a polybutylene terephthalate resin and a block copolymer of a polyether and polyethylene terephthalate.

CONSTITUTION: (A) 100pts.wt. polybutylene terephthalate having preferably 0.6W1.5 logarithmic viscosity (in a mixed solvent of phenol/tetrachloroethane in a weight ratio of 1/1 at 25°C in 0.5g/dl concentration) is blended with (B) 10W25pts.wt. block copolymer (one having preferably 0.5W1.4 logarithmic viscosity) of a polyether (preferably adduct of bisphenol with alkylene oxide) having 600W2,000mol.wt. and polyethylene terephthalate, having 10W55wt%, preferably 15W55wt% polyether content and, if necessary, various additives to give the aimed composition.