A semiconductor device improved in deterioration detection accuracy by using an inductance of a bonding wire. The semiconductor device includes a first conductor pattern formed on the insulating substrate, the main current of the semiconductor die device flowing through the first conductor pattern; a second conductor pattern formed on the insulating substrate for sensing the potential of the surface electrode of the semiconductor die device; a first bonding wire for connecting the surface electrode and the first conductor pattern; and a second bonding wire. Further, there is a voltage sensing unit which is connected to the first conductor pattern and the second conductor pattern to sense a potential difference between the first conductor pattern and the second conductor pattern at the time of switching of the semiconductor die device; and a deterioration detection unit for detecting deterioration of the first bonding wire by using the sensed potential difference.