PURPOSE: To provide an epoxy resin compsn. excellent in light transmission and suitable for optical applications.

CONSTITUTION: A transparent epoxy resin compsn. having a light transmission of 70% or higher in the visible range of wavelengths of 380nm or higher is obtd. by compounding an epoxy resin obtd. by epoxidizing all the double bonds of a polyoctenamer having a number-average mol.wt. of 1,000-5,000 and a satd. acid anhydride and curing the resulting compsn.