Semiconductor encapsulating epoxy resin compositions comprising an epoxy resin, a phenolic resin curing agent, a fire retardant comprising zinc molybdate carried on spherical silica having a mean particle diameter of 0.2-20 &mgr;m and a specific surface of 1-20 m2/g, and an inorganic filler are able to provide cured products having excellent fire retardance. The compositions have good flow and curing properties and excellent reliability and do not pose a hazard to human health or the environment.