An encapsulating resin composition contains a thermosetting resin component, a curing accelerator, an inorganic filler, an ion trapping agent, and an aromatic monocarboxylic acid having one or more electron-withdrawing functional groups selected from a nitro group and a cyano group. The encapsulating resin composition is solid at 25° C., and has a sulfur content, measured by X-ray fluorescence analysis, of 0.1 mass % or less in terms of SO3.