The present invention relates to an epoxy resin composition for an optical semiconductor device having an optical semiconductor element mounting region and having a reflector that surrounds at least a part of the region, the epoxy resin composition being an epoxy resin composition for forming the reflector, the epoxy resin composition including the following ingredients (A) to (E): (A) an epoxy resin; (B) a curing agent; (C) a white pigment; (D) an inorganic filler; and (E) a specific release agent.