To provide a polyphenylene ether-based resin composition which has improved processability and gives molded articles having excellent surfaces.

This polyphenylene ether-based resin composition comprises 100 pts.wt. of (A-1) a polyphenylene ether-based resin or (A-1) the polyphenylene ether-based resin and (A-2) a polystyrene-based resin, and (B) polytetrafluoroethylene-containing mixture powder comprising polytetrafluoroethylene particles having particle diameter of ≤10 μm and an organic polymer so that the content of the polytetrafluoroethylene component is 0.0001-20 pts.wt.