Polyfunctional monomers are disclosed that yield transparent resins having high transparency and excellent surface hardness and heat resistance. The present polyfunctional monomers are represented by the general formula (I): ##STR1## wherein R represents a group having a carbamido group or an oxazolidone group that will be bonded to the dimethylbenzyl group of the formula (I) and an acryl group or methacryl group at the other end. Control of the polymerization of the polyfunctional monomers is easy, and polymerization of the polyfunctional monomers yield and resins having excellent surface hardness, heat resistance, and workability, and having high transparency. The resins are well adapted for use as glazing materials, optical lenses, and optical disc substrates.