A polyphenylene sulfide resin composition includes (a) a polyphenylene sulfide resin and (b) a silicone-based polymer; the content of the component (b) is not less than 3 parts by weight and not more than 40 parts by weight with respect to 100 parts by weight of the component (a); in terms of morphology (phase structure), the polyphenylene sulfide resin composition has a phase-separated structure wherein the component (a) forms a continuous phase and the component (b) forms a dispersed phase in which the component (b) is dispersed with a number average dispersion diameter of not more than 3.0 μm; a test specimen obtained by injection molding of the polyphenylene sulfide resin composition at a cylinder temperature of 310° C. and a mold temperature of 145° C. has a flexural modulus of not more than 3.0 GPa as determined by a flexural test according to ISO 178.