A semiconductor device includes a lead frame 1 having a first lead 6, a second lead 7 and a third lead 8. A power transistor 2 is placed on the first lead 6, and the power transistor 2 is connected to the first lead 6. The power transistor 2 has a drain electrode on one side opposite to a first lead 6 side, and this drain electrode is connected to a Cu chip 3 on the power transistor 2. The Cu chip 3 is connected to the second lead 7 via Al wires 4. As a result, during wire bonding of the Al wires 4, it becomes possible to absorb shocks due to wire bonding by the Cu chip 3, or disperse pressure due to wire bonding by the Cu chip 3, or diffuse heat due to wire bonding by the Cu chip 3.