Epoxy resin compositions comprising (A) an epoxy resin having an epoxy equivalent of at least 185 and possessing a structure in which two benzene rings can be directly conjugated, carbon atoms having an sp2 type atomic orbital accounting for at least 50% of all the carbon atoms, (B) a &bgr;-naphthol type phenolic resin curing agent, (C) a curing accelerator, and (D) an inorganic filler cure into products having satisfactory solder crack resistance on use of lead-free solder and improved flame retardance despite the absence of halogenated epoxy resins and antimony compounds and are thus suited for semiconductor encapsulation.