To obtain the subject composition that contains a crown ether in this resin composition in a specific proportion, can manifest excellent high- temperature storage properties and realizes semiconductor sealing of high reliability with no occurrence of poor conduction even at elevated temperature.

This composition comprises (A) an epoxy resin, (B) a phenolic resin curing agent, (C) a cure promoting agent, for example, a tertiary amine, an imidazole or an organophosphorus compound, (D) an inorganic filler such as crystalline silica, alumina or glass fiber and (E) a crown ether of the formula such a 18-crown-6 where the amount of the component E is 0.5-3.0wt.% in this composition, metallic cation are captured by the molecular hole in the component E to suppress the chemical change in the gold line and aluminum pad thereby suppressing the deterioration of semiconductors while they are stored at elevated temperature. In addition, the content of the component E is set to the upper limit to inhibit the increase in the moisture absorption whereby the deterioration in resistance to soldering crack can be suppressed.