To provide an epoxy resin composition with a low absorbance at 400 nm, including an epoxy resin having a biphenyl backbone excellent in heat resistance, moisture resistance and impact resistance.

The epoxy resin composition for optical materials includes: an epoxy resin mixture obtained by subjecting a phenol resin mixture to glycidyl etherification, obtained by reacting a mixture or compound containing a compound represented by formula (2) (wherein X is a chlorine or bromine atom or a methoxy, ethoxy or hydroxy group) at a purity of 98-100 wt.% with a phenol, and a curing agent.