To obtain an epoxy resin composition for semiconductor device encapsulation, which lessens the warpages of an area packaging package, and a semiconductor device encapsulated with the epoxy resin composition, by a method wherein the composition contains epoxy resin, phenolic resin, a curing promotor and an inorganic filler, which are respectively specified as essential components.

An epoxy resin composition for semiconductor device encapsulation contains an epoxy resin, which is represented by formula I [where R2 is hydrogen, halogen or 11 to 12C of an alkyl group and amounts of the hydrogen, the halogen and the alkyl group may be the identical or may be different from each other] containing 30 to 100 wt.% of an epoxy resin in the total epoxy resin, phenolic resin having more than two of phenolic hydroxyl groups in one molecule, a curing promotor which is shown by formula II [where R2 is a phenyl group or a naphthyl group], and 80 to 92 wt.% of an inorganic filler being contained in the total epoxy resin composition as its essential components. This resin composition is superior in moldability, such as deformation of a gold wire, warpage of a semiconductor device encapsulated with the resin composition in a soldering process is little, and the reliability of the resistance to temperature cyclicity or the like of the device is high.