PURPOSE: To improve turn-off characteristics with the impedance of a surface lowered by providing a gate region surrounding an emitter region and projecting radially, and by forming a cathode electrode via a region of high impurity density in the emitter short structure.

CONSTITUTION: On P-type semiconductor substrate P1, N-type layer N1 and P-tupe layer P12 as a gate region are grown by being stacked, and at the center of the surface layer of layer P12, N-type auxiliary thyristor region N13 and N-type emitter region N12 surrounding it are diffusion-formed. On the surface layer part of layer P12, a plural number of P-type cathode regions P22 are diffusion-formed surrounding regions N12 and N13 and projecting radially and on it, P+-type region P22 for excellent contact with cathode electrode K is also diffusion-formed. Then, cathode electrode K extending from region P22' onto region N12, auxiliary cathode electrode Ks from region P22 onto region N13, gate electrode G on center region P22, and anode electrode A on the entire reverse surface of substrate P1 are fitted respectively.