In an epoxy resin composition comprising (A) an epoxy resin, (B) a curing
agent, (C) an inorganic compound, and (D) an inorganic filler, the
inorganic compound (C) is an oxide of metal elements at least one of
which is a metal element of Group II in the Periodic Table having a
second ionization potential of up to 20 eV, typically Zn.sub.2SiO.sub.4,
ZnCrO.sub.4, ZnFeO.sub.4 or ZnMoO.sub.4. When used for semiconductor
encapsulation, the epoxy resin composition is highly reliable and cures
into a product which is effective for minimizing electrical failure such
as defective insulation due to a copper migration phenomenon.