To provide an active energy ray-curable resin composition for coating an optical fiber that is excellent in adhesion to glass, curability, moist heat resistance and low moisture absorption.

The active energy ray-curable resin composition for coating an optical fiber comprises (A) a urethane (meth)acrylate produced by reacting (a) a polyester diol containing a 2-ethyl-2-alkyl-1,3-propanediol, (b) a polyisocyanate and (c) a hydroxy group-containing (meth)acrylate and (B) a (meth)acryloyl group-containing compound. The optical fiber having a cured coating film formed by using the resin composition is produced.