A polyamide resin composition for part of an engine cooling water system contains 100 parts by weight of a polyamide resin made of(A) from 50 to 98% by weight of nylon 66, (B) from 1 to 30% by weight of an aromatic polyamide resin, and (C) from 1 to 20% by weight of nylon 12; and (D) from 5 to 150 parts by weight of an inorganic filler, with the total content of nylon 66, the aromatic polyamide resin and nylon 12 being 100% by weight.