A heat-curable silicone resin-epoxy resin composition that is ideal as a premolded package for a high-brightness LED or solar cell. The composition contains (A) a heat-curable silicone resin, (B) a combination of a triazine derivative epoxy resin and an acid anhydride, or a prepolymer obtained by reaction of them, (C) an inorganic filler, and (D) a curing accelerator. The composition exhibits excellent curability, and yields a uniform cured product that displays excellent retention of heat resistance and light resistance over long periods of time, and suffers minimal yellowing.