PURPOSE: To obtain a polyphenylenesulfide resin composition containing a diene- based block polymer having internal epoxy in a polyphenylenesulfide resin and excellent in impact resistance and heat resistance.

CONSTITUTION: This polyphenylenesulfide resin composition is composed of (a) 50-99wt.% polyphenylenesulfide and (b) 1-50wt.% epoxidized diene-based block copolymer, and (c) a phenolic polymer compound having a phenol group in an amount of 0-30 pts.wt. based on 100 pts.wt. total amount of these components (a) and (b) at main chain or side chain, an (d) and epoxy group- opening reaction promoter in an amount of 0.01-5wt.% based on the component (b) may be added to the composition.