Resin sheet for sealing electronic component, resin-sealed semiconductor device, and production method for resin-sealed semiconductor device

This resin sheet for sealing an electronic component is used to produce a resin-sealed semiconductor device, includes, with respect to the whole resin sheet for sealing the electronic component, 70-93 weight% of an inorganic filler, and, after having been thermally cured when the thickness thereof is set to 250 µm, has a water vapour transmission rate under conditions in which the temperature is 85˚C and the humidity is 85%, for a period of 168 hours, of not more than 300 g/m 2 /24 hours.