The present invention is a polyphenylene sulfide resin composition comprising (a) a polyphenylene sulfide resin and (b) an olefin-based resin, and satisfying the following conditions (i) through (v): (i) The mixing ratio of the polyphenylene sulfide resin (a) and the olefin-based resin (b) is such that the amount of the polyphenylene sulfide resin (a) is in a range from 95 to 60 wt %, while the amount of the olefin-based resin (b) is in a range from 5 to 40 wt %, with the total weight of both the ingredients as 100 wt %; (hi) said olefin-based resin (b) comprising two copolymer: (b-1) an epoxy group-containing olefin copolymer and (b-2) an ethylene/(-olefin copolymer obtained by copolymerizing ethylene and an -olefin having 3 to 20 carbon atoms; (iii) as the morphology observed by an electron microscope, said polyphenylene sulfide resin (a) forms a continuous phase, and said olefin-based resin (b) forms a dispersion phase and has a core-shell structure having said ethylene/-olefin copolymer (b-2) acting as a core component contained in said epoxy group-containing olefin copolymer (b-1) acting as a shell component: (iv) the melt flow rate measured at a temperature of 315.5 C. and at a load of 5000 g according to ASTM-D-1238 is in a range from 10 to 50 g/10 min; and (v) the notched impact strength measured at -40 C. according to ASTM-D-256 is 300 J/m or more. This invention provides a PPS resin composition excellent in flowability, impact properties and low-temperature roughness and suitable for injection molding.