Epoxy resin composition, semiconductor sealant and semiconductor device

An epoxy resin composition characterized by including (A) an epoxy resin, (B) a curing agent, (C) 0.1-10% by mass of a silica filler having an average particle diameter of 10-100 nm, and (D) 40-75% by mass of a silica filler having an average particle diameter of 0.3-5 [mu]m, the epoxy resin composition including a total of 40.1-77% by mass of component (C) and component (D).