A semiconductor device, including: a semiconductor chip having a plurality of main electrodes and a gate electrode; a first substrate on which the semiconductor chip is mounted; a second substrate located above the first substrate, the second substrate having a conductive plate on a front surface thereof, the conductive plate being electrically connected to the semiconductor chip; and a case having an opening in an upper surface thereof, at least a part of the conductive plate being exposed through the opening, the case incorporating the semiconductor chip, the first substrate, and the second substrate.