Abstract: The present invention provides a material for optical lenses which not only sufficiently has properties such as impact resistance and dye-affinity essential for the optical lenses but also simultaneously attains a high refractive index, a high Abbe's number and a low specific gravity, and which is photopolymerizable. The present invention further provides a lens made of a synthetic resin which is a copolymer obtained by copolymerizing a composition comprising 20 to 80% by weight of bis-2-methacryloylthioethyl sulfide represented by the following structural formula (1), 5 to 50% by weight of a bifunctional or multifunctional thiol and 0 to 75% by weight of a monomer copolymerizable with these compounds, and which has a refractive index of 1.58 or more, an Abbe's number of 35 or more and a specific gravity of 1.35 or less: CH2═C(CH3)COSCH2CH2SCH2CH2SCOC(CH3)═CH2  Structural formula (1).

Abstract: The present invention provides a material for optical lenses which not only sufficiently has properties such as impact resistance and dye-affinity essential for the optical lenses but also simultaneously attains a high refractive index, a high Abbe's number and a low specific gravity, and which is photopolymerizable.