To provide a composition of an alicyclic structure=containing polymer, which gives a molded body excellent in impact resistance and surface smoothness, heat-resistant and having comparatively good transparency.

The resin composition comprises (A) more than 20 wt.% but less than 98.5 wt.% of an alicyclic structure-containing polymer and (B) less than 80 wt.% but more than 1.5 wt.% of a copolymer of raw monomers containing an α-olefin and a vinyl aromatic compound.