This polymerizable composition contains a polymerization reactive compound (A) and an internal mold release agent (B) that contains a polyether-modified silicone compound (b1) represented by general formula (1) and a polyether-modified silicone compound (b2) represented by general formula (2); and the polymerization reactive compound (A) is composed of one or more compounds that are selected fromamong polyiso(thio)cyanate compounds, poly(thio)epoxy compounds, polyoxetanyl compounds, polythietanyl compounds, alkyne compounds, poly(thi)ol compounds, polyamine compounds, acid anhydrides and polycarboxylic acid compounds.