A semiconductor device includes a transistor; a diode configured to be connected in reverse-parallel with the transistor; a sense transistor configured to generate a sense current depending on a current flowing in the transistor; a sense diode configured to generate a sense diode current depending on a current flowing in the diode; a resistor part configured to have one terminal connected with an emitter of the sense transistor and an anode of the sense diode, and another terminal connected with an emitter of the transistor and an anode of the diode, and to have the sense current or the sense diode current flow in the resistor part; and a resistance value control unit configured to differentiate a resistance value of the resistor part for a case where the sense current flows in the resistor part, and for a case where the sense diode current flows in the resistor part.