The present invention is a polymer composition comprising a hydrogenated crystalline cycloolefin ring-opening polymer (A) that comprises a repeating unit derived from a polycyclic norbornene-based monomer that includes three or more rings, 5 to 100 parts by weight of a glass filler (B) based on 100 parts by weight of the hydrogenated crystalline cycloolefin ring-opening polymer (A), and 5 to 20 parts of a metal oxide (C) based on 100 parts by weight of the hydrogenated crystalline cycloolefin ring-opening polymer (A), and a formed article. The polymer composition according to the present invention exhibits excellent electrical properties (low dielectric loss tangent), excellent adhesion to plating, and excellent reflow heat resistance, and can maintain strength even when subjected to high-temperature/high-humidity conditions.