The present invention provides a polybutylene terephthalate resin composition which does not induce swelling and bleeding of elastomer component caused by an organic solvent such as fuel, having performance of a high durability and the like in a cold cycle environment, and having an excellent resistance to hydrolysis. Specifically, relative to 100 parts by weight of a polybutylene terephthalate resin (A) having 30 meq/kg or less of the amount of terminal carboxyl groups, there are added a carbodiimide compound (B) in an amount of 0.3 to 1.5 equivalents of the carbodiimide functional group when the amount of carboxyl terminal group in the polybutylene terephthalate resin (A) is set as 1, and 20 to 100 parts by weight of a fibrous filler (C).