Provided are: a polymerizable composition from which a cured product having high transparency and minimal coloring can be obtained; and a method for producing the polymerizable composition. The polymerizable composition comprises: at least one polyfunctional acrylamide compound selected from the group consisting of a compound represented by general formula (1) and a compound represented by generalformula (2); and an alkali metal ion, the content of the alkali metal ion being 0.01 to 2 mass% relative to the total of the content of the polyfunctional acrylamide compound and the content of the alkali metal ion.