A novel resin composition improved in moldability and impact resistance, comprising (A) a polyphenylene oxide having a molecular weight of 5,000 or higher, (B) an aromatic hydrocarbon-formaldehyde resin or a modified aromatic hydrocarbon-formaldehyde resin, and, if necessary, (C) a rubbery polymer, the weight ratio of the resin (A) to the resin (B) being from 10:90 to 99:1 and the amount of the rubbery polymer (C) being 3 to 40 parts by weight per 100 parts by weight of the sum of the resins (A) and (B). This resin composition has excellent mechanical and electrical properties of the polyphenylene oxide together with an improved moldability, impact resistance, and adhesiveness.