PURPOSE: To obtain the titled lens having improved transparency, resistance to scuffing, and weather resistance in good molding properties, by polymerizing a mixture of a polymerization solution obtained by polymerizing preliminarily dimethacryl phthalate under a specific condition, a specific monomer and a polymerization initiator in a mold.

CONSTITUTION: A mixture of (A) 100pts.wt. polymerization solution obtained by polymerizing preliminarily dimethacryl phthalate in the presence of a polymerization initiator (e.g., organic peroxide, etc.) in such a way that a refractive index at D-line at 20°C is <1.5250, (B) preferably 0.5W30pts.wt. monomer (e.g., phenyl acrylate, etc.) shown by the formula (R1 and R2 are H, or methyl; m and n are 0W3), and (C) preferably 0.05W5pts.wt. radical polymerization initiator is cast into a lens mold, and then polymerized, to give the aimed lens.