There is provided a resin-sealed semiconductor device (BGA type semiconductor device) whose heat dissipating characteristic is improved, so that it is prevented from deteriorating in reliability. This BGA type semiconductor device includes a wiring substrate on a predetermined area on which a semiconductor chip is mounted; a plurality of metal bumps that are formed to be arranged at predetermined intervals in an area of the substrate different from the area on which the semiconductor chip is mounted; and a sealing resin layer that covers at least the semiconductor chip. Each of the plurality of metal bumps is covered with the sealing resin layer described above, with a part thereof exposed at a top face of the sealing resin layer.