A semiconductor device, including: a semiconductor substrate; a first semiconductor layer provided at a first surface of the semiconductor substrate; a plurality of first semiconductor regions selectively provided at a first surface of the first semiconductor layer; a plurality of trenches penetrating through the first semiconductor regions and the first semiconductor layer, and reaching the semiconductor substrate; a plurality of gate insulating films provided in the plurality of trenches, respectively; a plurality of gate electrodes provided in the plurality of trenches via the gate insulating films, respectively; an interlayer insulating film provided on the gate electrodes; a first electrode provided on the plurality of first semiconductor regions and the first semiconductor layer; a second electrode provided at a second surface of the semiconductor substrate; and a plurality of tetra ethoxy silane (TEOS) or spin-on-glass (SOG) films embedded in the plurality of gate electrodes in the plurality of trenches, respectively.