A semiconductor device in which a first semiconductor unit and a plurality of IGBT chips formed on a silicon semiconductor substrate are mounted and connected on a common insulating substrate, the semiconductor unit having a large number of semiconductor chips formed by use of a wide gap semiconductor substrate and connected in parallel, and wherein: the semiconductor chips are integrated in such a manner that one principal surface of each of the semiconductor chips of one and the same kind is joined onto a first principal surface of a first common copper plate while a conductive block is joined to the other principal surface of each of the semiconductor chips; a first principal surface of a second common copper plate is joined onto the conductive blocks, an insulating resin is packed in between the first principal surface of the first common copper plate and the first principal surface of the second common copper plate while a second principal surface of the first common copper plate and a second principal surface of the second common copper plate are exposed from the insulating resin; wherein each of the semiconductor chips of the semiconductor unit is an SiC-diode chip in which a cathode electrode is formed on the one principal surface while an anode electrode is formed on the other principal surface; the cathode electrodes are joined to the first principal surface of the first common copper plate; the anode electrodes are joined to the first principal surface of the second common copper plate through the conductive blocks; the common insulating substrate joined to a base plate by solder includes a conductive pattern for connection to a collector terminal and another conductive pattern for connection to an emitter terminal and an additional conductive pattern for connection to a gate terminal; collector electrodes of each of the IGBT chips and the first common copper plate of the first semiconductor unit are joined on the conductive pattern by solder; the other conductive pattern is connected with an emitter electrode of the IGBT chip by a wire; the other conductive pattern is connected with the second common copper plate by another wire which is a flexible flat ribbon wire, a plurality of copper wires or aluminum wires; and gate pads of the IGBT chips are connected to the additional conductive pattern by wires. the semiconductor chips are integrated in such a manner that one principal surface of each of the semiconductor chips of one and the same kind is joined onto a first principal surface of a first common copper plate while a conductive block is joined to the other principal surface of each of the semiconductor chips; a first principal surface of a second common copper plate is joined onto the conductive blocks, an insulating resin is packed in between the first principal surface of the first common copper plate and the first principal surface of the second common copper plate while a second principal surface of the first common copper plate and a second principal surface of the second common copper plate are exposed from the insulating resin; wherein each of the semiconductor chips of the semiconductor unit is an SiC-diode chip in which a cathode electrode is formed on the one principal surface while an anode electrode is formed on the other principal surface; the cathode electrodes are joined to the first principal surface of the first common copper plate; the anode electrodes are joined to the first principal surface of the second common copper plate through the conductive blocks; the common insulating substrate joined to a base plate by solder includes a conductive pattern for connection to a collector terminal and another conductive pattern for connection to an emitter terminal and an additional conductive pattern for connection to a gate terminal; collector electrodes of each of the IGBT chips and the first common copper plate of the first semiconductor unit are joined on the conductive pattern by solder; the other conductive pattern is connected with an emitter electrode of the IGBT chip by a wire; the other conductive pattern is connected with the second common copper plate by another wire which is a flexible flat ribbon wire, a plurality of copper wires or aluminum wires; and gate pads of the IGBT chips are connected to the additional conductive pattern by wires.