A polyphenylene sulfide resin composition exhibits excellent initial toughness and toughness after a long-term high temperature treatment typified by a tensile elongation at break after a dry heat treatment without impairing mechanical strength, chemical resistance and electrical insulation properties. The polyphenylene sulfide resin composition includes 0.01 to 10 parts by weight of an organosilane compound and 0.01 to 5 parts by weight of a metal salt of phosphorus oxoacid based on 100 parts by weight of a polyphenylene sulfide resin, and a tensile elongation at break, which is measured in accordance with ASTM-D638 under the conditions of a tensile speed of 10 mm/min and an ambient temperature of 23° C. after treating at 200° C. for 500 hours using an ASTM No. 4 dumbbell test piece obtained by injection molding the composition, is 10% or more.