A semiconductor device comprising an organic substrate, at least one semiconductor chip provided on a surface of the substrate, and a cured resin composition encapsulating the semiconductor chip provided on the surface of the substrate, characterized in that an absolute value of a distance between an imaginary line connecting two diagonally opposite corners of the substrate and a highest or lowest position on the surface of the substrate between the corners is smaller than 600 μm, as measured with a laser three-dimensional measuring instrument, a total volume ratio of the semiconductor chip to the semiconductor device ranges from 18 to 50%, and the cured resin composition comprises an inorganic filler (C) in such an amount that a weight ratio of the inorganic filler (C) to a total weight of the cured resin composition ranges from 80 to 90%.