The present invention provides an epoxy resin composition exhibiting good workability in drilling, molding, and desmearing as well as good interlayer adhesion strength. This epoxy resin composition comprises an epoxy resin, a curing agent, and an inorganic filler. The epoxy resin is composed of a dicyclopentadiene-based epoxy resin and a novolac-based epoxy resin. The curing agent is a biphenyl-based phenol resin. The inorganic filler is composed of aluminum hydroxide and granular silica having an epoxy-silane treated surface. The epoxy resin composition contains 20 to 50% by weight of the granular silica. The epoxy resin composition contains 2 to 15% by weight, based on total weight of granular silica, of the aluminum hydroxide.