To provide a resin having remarkably improved heat-resistance without deteriorating the properties of an epoxy resin such as adhesiveness, electrical properties, mechanical properties and weather resistance and having weather resistance and heat-resistance at the same time, keeping the reliability in high-temperature operation and free from the yellowing problem caused by the thermal oxidation of the resin.

The epoxy resin composition is composed of (A) an epoxy resin, (B) an epoxy resin hardener, (C) a compound having one or more reactive unsaturated bonds in the molecule and (D) a cure accelerator.