A semiconductor device having a thyristor SCR with reduced turn-off time. A third semiconductor region of the second conductivity type (anode AN) and a fourth semiconductor region of the first conductivity type (anode gate AG) are formed in the top layer of a first semiconductor region; fifth semiconductor region of the first conductivity type (cathode CA) and sixth semiconductor region of the second conductivity type (cathode gate CG) are formed in the top layer of a second semiconductor region; a gate insulating film and gate electrode MG are formed on the second semiconductor region. When the thyristor is turned off from the on state, a higher potential than that on the anode is applied to the anode gate, and a diode made up of the anode and the anode gate inside the thyristor is made to conduct so as to control the potential of the anode during driving.