It is an object of the present invention to provide a polymerizable composition and a cured resin composition, linear expansion coefficients of which are significantly improved without impairment of the excellent properties such as heat resistance, mechanical strength and the like of norbornene-based resins. The present invention is a polymerizable composition, which comprises a polymerizable substance containing a norbornene-based monomer or oligomer as a main component, a metathesis polymerization catalyst and silica powder, the weight content of the silica powder being larger than the weight content of the polymerizable substance.