The invention provides a silicone-modified epoxy resin composition comprising a silicone-modified epoxy resin having at least two epoxy groups, obtained from hydrosilylation reaction of an alkenyl-containing epoxy compound with an organopolysiloxane, a silicone-modified phenolic resin having at least two phenolic hydroxyl groups, obtained from hydrosilylation reaction of an alkenyl-containing phenol compound with an organopolysiloxane, black pigment, and an inorganic filler. Because of excellent tracking resistance, the epoxy resin composition is suited for encapsulating semiconductor devices.