To obtain a semiconductor-sealing epoxy resin comps. having excellent ordinary-temp. shelf stability, flowability and soldering cracking resistance, and greatly improved in curing properties during molding by using a specific epoxy resin and a specific curing accelerator.

This resin compsn. comprises, as the indispensable components, an epoxy resin having a solftening point of 50 to 90°C and represented by formula (1) (wherein (n) is 0 to 6; and R is H, a halogen, or an alkyl), a phenolic resin curing agent having a softening point of 55 to 130°C, a curing accelerator of formula II (wherein R1 to R4 are each monovalent org. group; and at least one of Y1 to Y4 is a group resulting from a proton donor having at least one proton capable of being liberated out of the molecule from which one proton is liberated), and an inorg. filler, provided that it contains 70-92wt.% inorg. filler based on the whole compsn. The proton donor for the curing accelerator is pref. an arom. carboxylic acid having at least one carboxyl group per molecule.