PURPOSE: To improve the gate turn-off characteristics of the titled thyristor by a method wherein an auxiliary gate terminal being led out contacting to a gate electrode is provided, a pulse type positive gate voltage is applied to the main gate terminal, a positive gate voltage is applied first to the auxiliary gate terminal and then a negative gate voltage is applied, and an ON-OFF operation is performed.

CONSTITUTION: The gate turn-off thyristor of amplifying gate type consists of the first base layer 1 of conductive type, the second base 2 of P-conductive type, the first emitter layer 3 which is formed in P-conductive type on the main surface located on the opposite side of the main surface whereon the second base layer 2 is formed on the first base layer 1, a plurality of N-conductive type main emitter layer 14 formed on the second base layer 2, the first gate electrode 151G provided at a part on the surface of the second base layer 2, an N-conductive type auxiliary emitter layer 14s formed in N-conductive type between the second base layer 2 and the first gate electrode 151G, the second gate electrode 152G provided as a contact on each layer by extending from above the auxiliary emitter layer 14s toward the second base layer 2 located on the opposite side of the first gate electrode 151G, and a main emitter electrode 15m provided on the first emitter electrode 5E, which is formed on the first emitter layer, and a main emitter layer 14m.