The invention pertains to a polymerizable composition comprising a cycloolefin monomer, a coupling agent (A) that has a cycloolefin structure, a coupling agent (B) that includes at least one compound represented by a formula (1) (provided that the coupling agent (B) excludes the coupling agent (A)), a filler, and a metathesis polymerization catalyst, a weight ratio (coupling agent (A)/coupling agent (B)) of the coupling agent (A) to the coupling agent (B) being 0.1 to 1.5, (X)n-m-M-(Y)m  (1) wherein M is a silicon atom, a titanium atom, an aluminum atom, or a zirconium atom, X is a hydrolyzable group, Y is a hydrocarbon group having 1 to 50 carbon atoms that is unsubstituted or substituted with a substituent that includes an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or a silicon atom, provided that at least one Y is a group having a solubility parameter value (SP value) of 7.5 to 10, m is an integer from 1 to 3, and n is a valence of M. A resin formed article that exhibits excellent heat resistance and impact resistance can be obtained by utilizing the polymerizable composition.