<p>A filler to be dispersed, as an inorganic material, in a thermosetting resin to produce an electronic component sealing agent, is composed of crystalline silicon dioxide particles. Not less than 70 wt-% of the crystalline silicon dioxide particles have the major-to-minor-axis ratio in the range of 1.20-1.40 and the circularity in the range of 0.75-0.90.</p>
