An objective of this invention is to provide an epoxy resin composition for encapsulating a semiconductor free from a harmful substance out of regard for the environment, which exhibits excellent soldering heat resistance and a higher productivity, as well as a semiconductor device manufactured by encapsulating therewith. This invention relates to a epoxy resin composition for encapsulating a semiconductor comprising, as essential components, (A) an epoxy resin having a particular structure and (B) a phenolic resin comprising a phenolic resin component having a particular structure as a main component, which contains a component having up to three aromatic rings in one molecule in 0.8% or less in an area ratio as determined by GPC analysis, as well as a semiconductor device manufactured by encapsulating a semiconductor chip with the composition.