To provide a resin composition for optical materials curable in two steps and excellent in transparency with little contraction before and after curing.

The resin composition for optical materials is characterized by including at least 10-80 pts.wt. of (A) polyisocyanates and/or (B) urethane prepolymers having an isocyanate terminal, 10-80 pts.wt. of (C) polyols and 5-30 pts.wt. of (D) a urethane (meth)acrylate resin.